6942291632

Committed 21 Nov 2023 10:14AM UTC coverage: 91.59% (+0.01%) from 91.58%

Build # 6942291632

Build Type

Pull #620

github

Committed by

web-flow

Commit Message

Merge 5f16b41c2 into dd07d62fd

Pull Request Pull Request #620: Implement switch expression

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93.09

/src/parsing/compileAstToExpression.ts

import CurlyArrayConstructor from '../expressions/arrays/CurlyArrayConstructor';
import SquareArrayConstructor from '../expressions/arrays/SquareArrayConstructor';
import AncestorAxis from '../expressions/axes/AncestorAxis';
import AttributeAxis from '../expressions/axes/AttributeAxis';
import ChildAxis from '../expressions/axes/ChildAxis';
import DescendantAxis from '../expressions/axes/DescendantAxis';
import FollowingAxis from '../expressions/axes/FollowingAxis';
import FollowingSiblingAxis from '../expressions/axes/FollowingSiblingAxis';
import ParentAxis from '../expressions/axes/ParentAxis';
import PrecedingAxis from '../expressions/axes/PrecedingAxis';
import PrecedingSiblingAxis from '../expressions/axes/PrecedingSiblingAxis';
import SelfAxis from '../expressions/axes/SelfAxis';
import IfExpression from '../expressions/conditional/IfExpression';
import { SequenceMultiplicity, SequenceType, ValueType } from '../expressions/dataTypes/Value';
import QName from '../expressions/dataTypes/valueTypes/QName';
import StackTraceGenerator, { SourceRange } from '../expressions/debug/StackTraceGenerator';
import Expression, { RESULT_ORDERINGS } from '../expressions/Expression';
import FlworExpression from '../expressions/FlworExpression';
import ForExpression from '../expressions/ForExpression';
import FunctionCall from '../expressions/functions/FunctionCall';
import InlineFunction from '../expressions/functions/InlineFunction';
import LetExpression from '../expressions/LetExpression';
import Literal from '../expressions/literals/Literal';
import MapConstructor from '../expressions/maps/MapConstructor';
import NamedFunctionRef from '../expressions/NamedFunctionRef';
import BinaryOperator, {
        BinaryEvaluationFunction,
        generateBinaryOperatorFunction,
} from '../expressions/operators/arithmetic/BinaryOperator';
import Unary from '../expressions/operators/arithmetic/Unary';
import AndOperator from '../expressions/operators/boolean/AndOperator';
import OrOperator from '../expressions/operators/boolean/OrOperator';
import GeneralCompare from '../expressions/operators/compares/GeneralCompare';
import NodeCompare from '../expressions/operators/compares/NodeCompare';
import ValueCompare from '../expressions/operators/compares/ValueCompare';
import IntersectExcept from '../expressions/operators/IntersectExcept';
import SequenceOperator from '../expressions/operators/SequenceOperator';
import SimpleMapOperator from '../expressions/operators/SimpleMapOperator';
import CastableAsOperator from '../expressions/operators/types/CastableAsOperator';
import CastAsOperator from '../expressions/operators/types/CastAsOperator';
import InstanceOfOperator from '../expressions/operators/types/InstanceOfOperator';
import Union from '../expressions/operators/Union';
import OrderByExpression from '../expressions/OrderByExpression';
import AbsolutePathExpression from '../expressions/path/AbsolutePathExpression';
import ContextItemExpression from '../expressions/path/ContextItemExpression';
import PathExpression from '../expressions/path/PathExpression';
import PossiblyUpdatingExpression from '../expressions/PossiblyUpdatingExpression';
import Filter from '../expressions/postfix/Filter';
import Lookup from '../expressions/postfix/Lookup';
import UnaryLookup from '../expressions/postfix/UnaryLookup';
import QuantifiedExpression from '../expressions/quantified/QuantifiedExpression';
import KindTest from '../expressions/tests/KindTest';
import NameTest from '../expressions/tests/NameTest';
import PITest from '../expressions/tests/PITest';
import TestAbstractExpression from '../expressions/tests/TestAbstractExpression';
import TypeTest from '../expressions/tests/TypeTest';
import { Bucket, intersectBuckets } from '../expressions/util/Bucket';
import VarRef from '../expressions/VarRef';
import WhereExpression from '../expressions/WhereExpression';
import DeleteExpression from '../expressions/xquery-update/DeleteExpression';
import InsertExpression, { TargetChoice } from '../expressions/xquery-update/InsertExpression';
import RenameExpression from '../expressions/xquery-update/RenameExpression';
import ReplaceExpression from '../expressions/xquery-update/ReplaceExpression';
import TransformExpression from '../expressions/xquery-update/TransformExpression';
import AttributeConstructor from '../expressions/xquery/AttributeConstructor';
import CommentConstructor from '../expressions/xquery/CommentConstructor';
import ElementConstructor from '../expressions/xquery/ElementConstructor';
import PIConstructor from '../expressions/xquery/PIConstructor';
import TextConstructor from '../expressions/xquery/TextConstructor';
import TypeSwitchExpression from '../expressions/xquery/TypeSwitchExpression';
import SwitchExpression from '../expressions/xquery/SwitchExpression';
import astHelper, { IAST } from './astHelper';

const COMPILATION_OPTIONS = {
        XPATH_MODE: { allowXQuery: false, allowUpdating: false },
        XQUERY_MODE: { allowXQuery: true, allowUpdating: false },
        XQUERY_UPDATING_MODE: { allowXQuery: true, allowUpdating: true },
};

function disallowUpdating(compilationOptions: CompilationOptions) {
        if (!compilationOptions.allowXQuery) {
                return COMPILATION_OPTIONS.XPATH_MODE;
        }
        if (!compilationOptions.allowUpdating) {
                return COMPILATION_OPTIONS.XQUERY_MODE;
        }
        return COMPILATION_OPTIONS.XQUERY_UPDATING_MODE;
}

type CompilationOptions = { allowUpdating?: boolean; allowXQuery?: boolean };

function compile(ast: IAST, compilationOptions: CompilationOptions): Expression {
        const name = ast[0];
        switch (name) {
                // Operators
                case 'andOp':
                        return andOp(ast, compilationOptions);
                case 'orOp':
                        return orOp(ast, compilationOptions);
                case 'unaryPlusOp':
                        return unaryPlus(ast, compilationOptions);
                case 'unaryMinusOp':
                        return unaryMinus(ast, compilationOptions);
                case 'addOp':
                case 'subtractOp':
                case 'multiplyOp':
                case 'divOp':
                case 'idivOp':
                case 'modOp':
                        return binaryOperator(ast, compilationOptions);
                case 'sequenceExpr':
                        return sequence(ast, compilationOptions);
                case 'unionOp':
                        return unionOp(ast, compilationOptions);
                case 'exceptOp':
                case 'intersectOp':
                        return intersectExcept(ast, compilationOptions);
                case 'stringConcatenateOp':
                        return stringConcatenateOp(ast, compilationOptions);
                case 'rangeSequenceExpr':
                        return rangeSequenceExpr(ast, compilationOptions);

                // Compares
                case 'equalOp':
                case 'notEqualOp':
                case 'lessThanOrEqualOp':
                case 'lessThanOp':
                case 'greaterThanOrEqualOp':
                case 'greaterThanOp':
                        return compare('generalCompare', ast, compilationOptions);
                case 'eqOp':
                case 'neOp':
                case 'ltOp':
                case 'leOp':
                case 'gtOp':
                case 'geOp':
                        return compare('valueCompare', ast, compilationOptions);
                case 'isOp':
                case 'nodeBeforeOp':
                case 'nodeAfterOp':
                        return compare('nodeCompare', ast, compilationOptions);

                // Path
                case 'pathExpr':
                        return pathExpr(ast, compilationOptions);
                case 'contextItemExpr':
                        const type = astHelper.getAttribute(ast, 'type');
                        return new ContextItemExpression(type);

                // Functions
                case 'functionCallExpr':
                        return functionCall(ast, compilationOptions);
                case 'inlineFunctionExpr':
                        return inlineFunction(ast, compilationOptions);
                case 'arrowExpr':
                        return arrowExpr(ast, compilationOptions);
                case 'dynamicFunctionInvocationExpr':
                        return dynamicFunctionInvocationExpr(ast, compilationOptions);
                case 'namedFunctionRef':
                        return namedFunctionRef(ast, compilationOptions);

                // Literals
                case 'integerConstantExpr':
                        return integerConstantExpr(ast, compilationOptions);
                case 'stringConstantExpr':
                        return stringConstantExpr(ast, compilationOptions);
                case 'decimalConstantExpr':
                        return decimalConstantExpr(ast, compilationOptions);
                case 'doubleConstantExpr':
                        return doubleConstantExpr(ast, compilationOptions);

                // Variables
                case 'varRef':
                        return varRef(ast, compilationOptions);
                case 'flworExpr':
                        return flworExpression(ast, compilationOptions);

                // Quantified
                case 'quantifiedExpr':
                        return quantified(ast, compilationOptions);

                // Conditional
                case 'ifThenElseExpr':
                        return IfThenElseExpr(ast, compilationOptions);

                case 'instanceOfExpr':
                        return instanceOf(ast, compilationOptions);
                case 'castExpr':
                        return castAs(ast, compilationOptions);
                case 'castableExpr':
                        return castableAs(ast, compilationOptions);

                case 'simpleMapExpr':
                        return simpleMap(ast, compilationOptions);

                case 'mapConstructor':
                        return mapConstructor(ast, compilationOptions);

                case 'arrayConstructor':
                        return arrayConstructor(ast, compilationOptions);

                case 'unaryLookup':
                        const returnType = astHelper.getAttribute(ast, 'type');
                        return new UnaryLookup(compileLookup(ast, compilationOptions), returnType);

                case 'typeswitchExpr':
                        return typeswitchExpr(ast, compilationOptions);
                case 'switchExpr':
                        return switchExpr(ast, compilationOptions);

                // XQuery node constructors
                case 'elementConstructor':
                        return dirElementConstructor(ast, compilationOptions);
                case 'attributeConstructor':
                        return attributeConstructor(ast, compilationOptions);
                case 'computedAttributeConstructor':
                        return computedAttributeConstructor(ast, compilationOptions);
                case 'computedCommentConstructor':
                        return computedCommentConstructor(ast, compilationOptions);
                case 'computedTextConstructor':
                        return computedTextConstructor(ast, compilationOptions);
                case 'computedElementConstructor':
                        return computedElementConstructor(ast, compilationOptions);
                case 'computedPIConstructor':
                        return computedPIConstructor(ast, compilationOptions);
                case 'CDataSection':
                        return CDataSection(ast, compilationOptions);

                // XQuery update facility
                case 'deleteExpr':
                        return deleteExpression(ast, compilationOptions);
                case 'insertExpr':
                        return insertExpression(ast, compilationOptions);
                case 'renameExpr':
                        return renameExpression(ast, compilationOptions);
                case 'replaceExpr':
                        return replaceExpression(ast, compilationOptions);
                case 'transformExpr':
                        return transformExpression(ast, compilationOptions);

                case 'x:stackTrace':
                        return stackTrace(ast, compilationOptions);

                // Some simple aliases:
                case 'ifClause':
                case 'thenClause':
                case 'elseClause':
                        return compile(astHelper.getFirstChild(ast, '*'), compilationOptions);

                default:
                        return compileTest(ast, compilationOptions);
        }
}

function compileTest(ast: IAST, compilationOptions: CompilationOptions): TestAbstractExpression {
        switch (ast[0]) {
                // Tests
                case 'nameTest':
                        return nameTest(ast, compilationOptions);
                case 'piTest':
                        return piTest(ast, compilationOptions);
                case 'commentTest':
                        return commentTest(ast, compilationOptions);
                case 'textTest':
                        return textTest(ast, compilationOptions);
                case 'documentTest':
                        return documentTest(ast, compilationOptions);
                case 'attributeTest':
                        return attributeTest(ast, compilationOptions);
                case 'elementTest':
                        return elementTest(ast, compilationOptions);
                case 'anyKindTest':
                        return anyKindTest();
                case 'anyMapTest':
                        return anyMapTest(ast, compilationOptions);
                case 'anyArrayTest':
                        return anyArrayTest(ast, compilationOptions);
                case 'Wildcard':
                        return wildcard(ast, compilationOptions);
                case 'atomicType':
                        return typeTest(ast, compilationOptions);
                case 'anyItemType':
                        return anyItemTest();
                // case 'voidSequenceType':
                //         return voidSequenceTest();

                default:
                        throw new Error('No selector counterpart for: ' + ast[0] + '.');
        }
}

function stackTrace(ast: IAST, compilationOptions: CompilationOptions) {
        const innerExpression = ast[2] as IAST;

        // Do not make nested stacktraces at the same exact location. Just use the inner one
        let nextCompilableExpression: IAST = innerExpression;
        while (nextCompilableExpression[0] === 'x:stackTrace') {
                ast = nextCompilableExpression;
                nextCompilableExpression = nextCompilableExpression[2] as IAST;
        }

        const location = ast[1] as SourceRange;

        return new StackTraceGenerator(
                location,
                nextCompilableExpression[0],
                compile(nextCompilableExpression, compilationOptions),
                location.comment,
        );
}

function arrayConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        const arrConstructor = astHelper.getFirstChild(ast, '*');
        const members = astHelper
                .getChildren(arrConstructor, 'arrayElem')
                .map((arrayElem) =>
                        compile(astHelper.getFirstChild(arrayElem, '*'), disallowUpdating(compilationOptions)),
                );
        switch (arrConstructor[0]) {
                case 'curlyArray':
                        return new CurlyArrayConstructor(members, type);
                case 'squareArray':
                        return new SquareArrayConstructor(members, type);
                default:
                        throw new Error('Unrecognized arrayType: ' + arrConstructor[0]);
        }
}

function mapConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        return new MapConstructor(
                astHelper.getChildren(ast, 'mapConstructorEntry').map((keyValuePair) => ({
                        key: compile(
                                astHelper.followPath(keyValuePair, ['mapKeyExpr', '*']),
                                disallowUpdating(compilationOptions),
                        ),
                        value: compile(
                                astHelper.followPath(keyValuePair, ['mapValueExpr', '*']),
                                disallowUpdating(compilationOptions),
                        ),
                })),
                type,
        );
}

function unwrapBinaryOperator(
        operatorName: string,
        ast: IAST,
        compilationOptions: CompilationOptions,
) {
        const compiledAstNodes: Expression[] = [];
        function unwrapInner(innerAst: IAST) {
                const firstOperand = astHelper.getFirstChild(
                        astHelper.getFirstChild(innerAst, 'firstOperand') as IAST,
                        '*',
                ) as IAST;
                const secondOperand = astHelper.getFirstChild(
                        astHelper.getFirstChild(innerAst, 'secondOperand') as IAST,
                        '*',
                ) as IAST;

                if (firstOperand[0] === operatorName) {
                        unwrapInner(firstOperand);
                } else {
                        compiledAstNodes.push(compile(firstOperand as IAST, compilationOptions));
                }
                if (secondOperand[0] === operatorName) {
                        unwrapInner(secondOperand);
                } else {
                        compiledAstNodes.push(compile(secondOperand as IAST, compilationOptions));
                }
        }
        unwrapInner(ast);

        return compiledAstNodes;
}

function andOp(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        return new AndOperator(
                unwrapBinaryOperator('andOp', ast, disallowUpdating(compilationOptions)),
                type,
        );
}

function orOp(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        return new OrOperator(
                unwrapBinaryOperator('orOp', ast, disallowUpdating(compilationOptions)),
                type,
        );
}

function binaryOperator(ast: IAST, compilationOptions: CompilationOptions) {
        const kind = ast[0];
        const a = compile(
                astHelper.followPath(ast, ['firstOperand', '*']),
                disallowUpdating(compilationOptions),
        );
        const b = compile(
                astHelper.followPath(ast, ['secondOperand', '*']),
                disallowUpdating(compilationOptions),
        );

        const attributeType = astHelper.getAttribute(ast, 'type');
        const first = astHelper.getAttribute(astHelper.followPath(ast, ['firstOperand', '*']), 'type');
        const second = astHelper.getAttribute(
                astHelper.followPath(ast, ['secondOperand', '*']),
                'type',
        );

        let evaluateFunction: BinaryEvaluationFunction;
        if (first && second && astHelper.getAttribute(ast, 'type')) {
                evaluateFunction = generateBinaryOperatorFunction(kind, first.type, second.type);
        }

        return new BinaryOperator(kind, a, b, attributeType, evaluateFunction);
}

function compileLookup(ast: IAST, compilationOptions: CompilationOptions): '*' | Expression {
        const keyExpression = astHelper.getFirstChild(ast, '*');
        switch (keyExpression[0]) {
                case 'NCName':
                        return new Literal(astHelper.getTextContent(keyExpression), {
                                type: ValueType.XSSTRING,
                                mult: SequenceMultiplicity.EXACTLY_ONE,
                        });
                case 'star':
                        return '*';
                default:
                        return compile(keyExpression, disallowUpdating(compilationOptions));
        }
}

function castAs(ast: IAST, compilationOptions: CompilationOptions) {
        const expression = compile(
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'argExpr'), '*'),
                disallowUpdating(compilationOptions),
        );

        const singleType = astHelper.getFirstChild(ast, 'singleType');
        const targetType = astHelper.getQName(astHelper.getFirstChild(singleType, 'atomicType'));
        const optional = astHelper.getFirstChild(singleType, 'optional') !== null;

        return new CastAsOperator(expression, targetType, optional);
}

function castableAs(ast: IAST, compilationOptions: CompilationOptions) {
        const expression = compile(
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'argExpr'), '*'),
                disallowUpdating(compilationOptions),
        );

        const singleType = astHelper.getFirstChild(ast, 'singleType');
        const targetType = astHelper.getQName(astHelper.getFirstChild(singleType, 'atomicType'));
        const optional = astHelper.getFirstChild(singleType, 'optional') !== null;

        return new CastableAsOperator(expression, targetType, optional);
}

// Binary compare (=, !=, le, is, <<, >>, etc)
function compare(compareType: string, ast: IAST, compilationOptions: CompilationOptions) {
        const firstOperand = astHelper.followPath(ast, ['firstOperand', '*']);
        const secondOperand = astHelper.followPath(ast, ['secondOperand', '*']);

        const firstExpression = compile(firstOperand, disallowUpdating(compilationOptions));
        const secondExpression = compile(secondOperand, disallowUpdating(compilationOptions));

        switch (compareType) {
                case 'valueCompare':
                        return new ValueCompare(ast[0], firstExpression, secondExpression);
                case 'nodeCompare':
                        return new NodeCompare(ast[0], firstExpression, secondExpression);
                case 'generalCompare':
                        return new GeneralCompare(ast[0], firstExpression, secondExpression);
        }
}

function IfThenElseExpr(ast: IAST, compilationOptions: CompilationOptions) {
        const retType = astHelper.getAttribute(ast, 'type');
        const ifClausePart =
                astHelper.getFirstChild(ast, 'ifClause') || astHelper.getChildren(ast, 'x:stackTrace')[0];
        const thenClausePart =
                astHelper.getFirstChild(ast, 'thenClause') || astHelper.getChildren(ast, 'x:stackTrace')[1];
        const elseClausePart =
                astHelper.getFirstChild(ast, 'elseClause') || astHelper.getChildren(ast, 'x:stackTrace')[2];

        return new IfExpression(
                compile(ifClausePart, disallowUpdating(compilationOptions)),
                compile(thenClausePart, compilationOptions) as PossiblyUpdatingExpression,
                compile(elseClausePart, compilationOptions) as PossiblyUpdatingExpression,
                retType,
        );
}

function forClause(
        expressionClause: IAST,
        compilationOptions: CompilationOptions,
        returnClauseExpression: PossiblyUpdatingExpression | FlworExpression,
): ForExpression {
        const forClauseItems = astHelper.getChildren(expressionClause, '*');
        let returnExpr = returnClauseExpression;

        for (let i = forClauseItems.length - 1; i >= 0; --i) {
                const forClauseItem = forClauseItems[i];
                const expression = astHelper.followPath(forClauseItem, ['forExpr', '*']);
                const positionalVariableBinding = astHelper.getFirstChild(
                        forClauseItem,
                        'positionalVariableBinding',
                );

                returnExpr = new ForExpression(
                        astHelper.getQName(
                                astHelper.followPath(forClauseItem, ['typedVariableBinding', 'varName']),
                        ),
                        compile(expression, disallowUpdating(compilationOptions)),
                        positionalVariableBinding ? astHelper.getQName(positionalVariableBinding) : null,
                        returnExpr,
                );
        }

        return returnExpr as ForExpression;
}

function letClause(
        expressionClause: IAST,
        compilationOptions: CompilationOptions,
        returnClauseExpression: PossiblyUpdatingExpression | FlworExpression,
): LetExpression {
        const letClauseItems = astHelper.getChildren(expressionClause, '*');
        let returnExpr = returnClauseExpression;

        for (let i = letClauseItems.length - 1; i >= 0; --i) {
                const letClauseItem = letClauseItems[i];
                const expression = astHelper.followPath(letClauseItem, ['letExpr', '*']);
                returnExpr = new LetExpression(
                        astHelper.getQName(
                                astHelper.followPath(letClauseItem, ['typedVariableBinding', 'varName']),
                        ),
                        compile(expression, disallowUpdating(compilationOptions)),
                        returnExpr,
                );
        }

        return returnExpr as LetExpression;
}

function whereClause(
        expressionClause: IAST,
        compilationOptions: CompilationOptions,
        returnClauseExpression: PossiblyUpdatingExpression | FlworExpression,
): WhereExpression {
        const whereClauseItems = astHelper.getChildren(expressionClause, '*');
        let returnExpr = returnClauseExpression;

        for (let i = whereClauseItems.length - 1; i >= 0; --i) {
                const whereClauseItem = whereClauseItems[i];
                returnExpr = new WhereExpression(compile(whereClauseItem, compilationOptions), returnExpr);
        }

        return returnExpr as WhereExpression;
}

function orderByClause(
        expressionClause: IAST,
        compilationOptions: CompilationOptions,
        returnClauseExpression: PossiblyUpdatingExpression,
): OrderByExpression {
        const orderBySpecs = astHelper.getChildren(expressionClause, '*');
        return new OrderByExpression(
                orderBySpecs
                        .filter((spec) => spec[0] !== 'stable')
                        .map((spec) => {
                                const orderModifier = astHelper.getFirstChild(spec, 'orderModifier');
                                const kind = orderModifier
                                        ? astHelper.getFirstChild(orderModifier, 'orderingKind')
                                        : null;
                                const mode = orderModifier
                                        ? astHelper.getFirstChild(orderModifier, 'emptyOrderingMode')
                                        : null;

                                const isAscending = kind ? astHelper.getTextContent(kind) === 'ascending' : true;
                                const isEmptyLeast = mode ? astHelper.getTextContent(mode) === 'empty least' : true;

                                return {
                                        expression: compile(
                                                astHelper.followPath(spec, ['orderByExpr', '*']),
                                                compilationOptions,
                                        ),
                                        isAscending,
                                        isEmptyLeast,
                                };
                        }),
                returnClauseExpression,
        );
}

function flworExpression(ast: IAST, compilationOptions: CompilationOptions) {
        const clausesAndReturnClause = astHelper.getChildren(ast, '*');
        const returnClauseExpression = astHelper.getFirstChild(
                clausesAndReturnClause[clausesAndReturnClause.length - 1],
                '*',
        );

        // Return intermediate and initial clauses handling
        const clauses = clausesAndReturnClause.slice(0, -1);

        // We have to check if there are any intermediate clauses before compiling them.
        if (clauses.length > 1) {
                if (!compilationOptions.allowXQuery) {
                        throw new Error('XPST0003: Use of XQuery FLWOR expressions in XPath is no allowed');
                }
        }

        return clauses.reduceRight(
                (returnOfPreviousExpression: PossiblyUpdatingExpression, flworExpressionClause: IAST) => {
                        switch (flworExpressionClause[0]) {
                                case 'forClause':
                                        return forClause(
                                                flworExpressionClause,
                                                compilationOptions,
                                                returnOfPreviousExpression,
                                        );
                                case 'letClause':
                                        return letClause(
                                                flworExpressionClause,
                                                compilationOptions,
                                                returnOfPreviousExpression,
                                        );
                                case 'whereClause':
                                        return whereClause(
                                                flworExpressionClause,
                                                compilationOptions,
                                                returnOfPreviousExpression,
                                        );
                                case 'windowClause':
                                        throw new Error(
                                                `Not implemented: ${flworExpressionClause[0]} is not implemented yet.`,
                                        );
                                case 'groupByClause':
                                        throw new Error(
                                                `Not implemented: ${flworExpressionClause[0]} is not implemented yet.`,
                                        );
                                case 'orderByClause':
                                        return orderByClause(
                                                flworExpressionClause,
                                                compilationOptions,
                                                returnOfPreviousExpression,
                                        );
                                case 'countClause':
                                        throw new Error(
                                                `Not implemented: ${flworExpressionClause[0]} is not implemented yet.`,
                                        );
                                default:
                                        throw new Error(
                                                `Not implemented: ${flworExpressionClause[0]} is not supported in a flwor expression`,
                                        );
                        }
                },
                compile(returnClauseExpression, compilationOptions),
        );
}

function functionCall(
        ast: IAST,
        compilationOptions: { allowUpdating?: boolean; allowXQuery?: boolean },
) {
        const functionName = astHelper.getFirstChild(ast, 'functionName');
        const functionArguments = astHelper.getChildren(astHelper.getFirstChild(ast, 'arguments'), '*');

        const returnType = astHelper.getAttribute(ast, 'type');

        return new FunctionCall(
                new NamedFunctionRef(
                        astHelper.getQName(functionName),
                        functionArguments.length,
                        returnType,
                ),
                functionArguments.map((arg) =>
                        arg[0] === 'argumentPlaceholder' ? null : compile(arg, compilationOptions),
                ),
                returnType,
        );
}

function arrowExpr(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        const argExpr = astHelper.followPath(ast, ['argExpr', '*']);
        // Each part an EQName, expression, or arguments passed to the previous part
        const parts = astHelper.getChildren(ast, '*').slice(1);

        let args = [compile(argExpr, compilationOptions)];
        for (let i = 0; i < parts.length; i++) {
                if (parts[i][0] === 'arguments') {
                        continue;
                }
                if (parts[i + 1][0] === 'arguments') {
                        const functionArguments = astHelper.getChildren(parts[i + 1], '*');
                        args = args.concat(
                                functionArguments.map((arg) =>
                                        arg[0] === 'argumentPlaceholder' ? null : compile(arg, compilationOptions),
                                ),
                        );
                }

                const func =
                        parts[i][0] === 'EQName'
                                ? new NamedFunctionRef(astHelper.getQName(parts[i]), args.length, type)
                                : compile(parts[i], disallowUpdating(compilationOptions));
                args = [new FunctionCall(func, args, type)];
        }
        return args[0];
}

function dynamicFunctionInvocationExpr(ast: IAST, compilationOptions: CompilationOptions) {
        const functionItemContent = astHelper.followPath(ast, ['functionItem', '*']);
        const retType = astHelper.getAttribute(ast, 'type');
        const argumentsAst = astHelper.getFirstChild(ast, 'arguments');
        let args: Expression[] = [];
        if (argumentsAst) {
                const functionArguments = astHelper.getChildren(argumentsAst, '*');
                args = functionArguments.map((arg) =>
                        arg[0] === 'argumentPlaceholder' ? null : compile(arg, compilationOptions),
                );
        }

        return new FunctionCall(compile(functionItemContent, compilationOptions), args, retType);
}

function namedFunctionRef(ast: IAST, _compilationOptions: CompilationOptions) {
        const functionName = astHelper.getFirstChild(ast, 'functionName');
        const type = astHelper.getAttribute(ast, 'type');
        const arity = astHelper.getTextContent(
                astHelper.followPath(ast, ['integerConstantExpr', 'value']),
        );
        return new NamedFunctionRef(astHelper.getQName(functionName), parseInt(arity, 10), type);
}

function inlineFunction(
        ast: IAST,
        compilationOptions: { allowUpdating?: boolean; allowXQuery?: boolean },
) {
        const params = astHelper.getChildren(astHelper.getFirstChild(ast, 'paramList'), '*');
        const functionBody = astHelper.followPath(ast, ['functionBody', '*']);
        const type = astHelper.getAttribute(ast, 'type');

        return new InlineFunction(
                params.map((param) => {
                        const td: {
                                name: QName;
                                type: SequenceType;
                        } = {
                                name: astHelper.getQName(astHelper.getFirstChild(param, 'varName')),
                                type: astHelper.getTypeDeclaration(param),
                        };
                        return td;
                }),
                astHelper.getTypeDeclaration(ast),
                functionBody
                        ? (compile(functionBody, compilationOptions) as PossiblyUpdatingExpression)
                        : new SequenceOperator([], type),
        );
}

function instanceOf(
        ast: IAST,
        compilationOptions: { allowUpdating?: boolean; allowXQuery?: boolean },
) {
        const expression = compile(astHelper.followPath(ast, ['argExpr', '*']), compilationOptions);
        const sequenceType = astHelper.followPath(ast, ['sequenceType', '*']);
        const occurrence = astHelper.followPath(ast, ['sequenceType', 'occurrenceIndicator']);
        const type = astHelper.getAttribute(ast, 'type');

        return new InstanceOfOperator(
                expression,
                compile(sequenceType, disallowUpdating(compilationOptions)),
                occurrence ? astHelper.getTextContent(occurrence) : '',
                type,
        );
}

function integerConstantExpr(ast: IAST, _compilationOptions: CompilationOptions) {
        return new Literal(astHelper.getTextContent(astHelper.getFirstChild(ast, 'value')), {
                type: ValueType.XSINTEGER,
                mult: SequenceMultiplicity.EXACTLY_ONE,
        });
}

function stringConstantExpr(ast: IAST, _compilationOptions: CompilationOptions) {
        return new Literal(astHelper.getTextContent(astHelper.getFirstChild(ast, 'value')), {
                type: ValueType.XSSTRING,
                mult: SequenceMultiplicity.EXACTLY_ONE,
        });
}

function decimalConstantExpr(ast: IAST, _compilationOptions: CompilationOptions) {
        return new Literal(astHelper.getTextContent(astHelper.getFirstChild(ast, 'value')), {
                type: ValueType.XSDECIMAL,
                mult: SequenceMultiplicity.EXACTLY_ONE,
        });
}

function doubleConstantExpr(ast: IAST, _compilationOptions: CompilationOptions) {
        return new Literal(astHelper.getTextContent(astHelper.getFirstChild(ast, 'value')), {
                type: ValueType.XSDOUBLE,
                mult: SequenceMultiplicity.EXACTLY_ONE,
        });
}

function nameTest(ast: IAST, _compilationOptions: CompilationOptions) {
        return new NameTest(astHelper.getQName(ast));
}

function anyKindTest() {
        return new TypeTest({ prefix: '', namespaceURI: null, localName: 'node()' });
}

function anyItemTest() {
        return new TypeTest({ prefix: '', namespaceURI: null, localName: 'item()' });
}

function pathExpr(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        const rawSteps = astHelper.getChildren(ast, 'stepExpr');
        let hasAxisStep = false;
        const steps = rawSteps.map((step) => {
                const axis = astHelper.getFirstChild(step, 'xpathAxis');

                let stepExpression: Expression;

                const children = astHelper.getChildren(step, '*');
                const postFixExpressions: (['lookup', '*' | Expression] | ['predicate', Expression])[] = [];
                let intersectingBucket: Bucket = null;
                let hasSeenNullBucket = false;
                for (const child of children) {
                        switch (child[0]) {
                                case 'lookup':
                                        postFixExpressions.push(['lookup', compileLookup(child, compilationOptions)]);
                                        break;
                                case 'predicate':
                                case 'predicates':
                                        for (const childPredicate of astHelper.getChildren(child, '*')) {
                                                const predicateExpression = compile(
                                                        childPredicate,
                                                        disallowUpdating(compilationOptions),
                                                );
                                                if (!hasSeenNullBucket) {
                                                        const predicateBucket = predicateExpression.getBucket();
                                                        if (predicateBucket === null) {
                                                                // If we see a null bucket, we cannot use any future buckets
                                                                // anymore. This filter may have been position-aware For example:
                                                                // `following-sibling::node()[1][self::xxx]` is not the same as
                                                                // `following-sibling::node()[self::xxx][1]`.
                                                                hasSeenNullBucket = true;
                                                        } else {
                                                                intersectingBucket = intersectBuckets(
                                                                        intersectingBucket,
                                                                        predicateBucket,
                                                                );
                                                        }
                                                }
                                                postFixExpressions.push(['predicate', predicateExpression]);
                                        }
                                        break;
                        }
                }

                if (axis) {
                        hasAxisStep = true;
                        const test = astHelper.getFirstChild(step, [
                                'attributeTest',
                                'anyElementTest',
                                'piTest',
                                'documentTest',
                                'elementTest',
                                'commentTest',
                                'namespaceTest',
                                'anyKindTest',
                                'textTest',
                                'anyFunctionTest',
                                'typedFunctionTest',
                                'schemaAttributeTest',
                                'atomicType',
                                'anyItemType',
                                'parenthesizedItemType',
                                'typedMapTest',
                                'typedArrayTest',
                                'nameTest',
                                'Wildcard',
                        ]);

                        const testExpression = compileTest(test, disallowUpdating(compilationOptions));
                        switch (astHelper.getTextContent(axis)) {
                                case 'ancestor':
                                        stepExpression = new AncestorAxis(testExpression, { inclusive: false });
                                        break;
                                case 'ancestor-or-self':
                                        stepExpression = new AncestorAxis(testExpression, { inclusive: true });
                                        break;
                                case 'attribute':
                                        stepExpression = new AttributeAxis(testExpression, intersectingBucket);
                                        break;
                                case 'child':
                                        stepExpression = new ChildAxis(testExpression, intersectingBucket);
                                        break;
                                case 'descendant':
                                        stepExpression = new DescendantAxis(testExpression, { inclusive: false });
                                        break;
                                case 'descendant-or-self':
                                        stepExpression = new DescendantAxis(testExpression, { inclusive: true });
                                        break;
                                case 'parent':
                                        stepExpression = new ParentAxis(testExpression, intersectingBucket);
                                        break;
                                case 'following-sibling':
                                        stepExpression = new FollowingSiblingAxis(testExpression, intersectingBucket);
                                        break;
                                case 'preceding-sibling':
                                        stepExpression = new PrecedingSiblingAxis(testExpression, intersectingBucket);
                                        break;
                                case 'following':
                                        stepExpression = new FollowingAxis(testExpression);
                                        break;
                                case 'preceding':
                                        stepExpression = new PrecedingAxis(testExpression);
                                        break;
                                case 'self':
                                        stepExpression = new SelfAxis(testExpression, intersectingBucket);
                                        break;
                        }
                } else {
                        // We must be a filter expression
                        const filterExpr = astHelper.followPath(step, ['filterExpr', '*']);
                        stepExpression = compile(filterExpr, disallowUpdating(compilationOptions));
                }

                for (const postfix of postFixExpressions) {
                        switch (postfix[0]) {
                                case 'lookup':
                                        stepExpression = new Lookup(stepExpression, postfix[1]);
                                        break;
                                case 'predicate':
                                        stepExpression = new Filter(stepExpression, postfix[1]);
                                        break;
                        }
                }

                stepExpression.type = type;
                return stepExpression;
        });

        const isAbsolute = astHelper.getFirstChild(ast, 'rootExpr');
        // If an path has no axis steps, we should skip sorting. The path
        // is probably a chain of filter expressions or lookups
        const requireSorting = hasAxisStep || isAbsolute !== null || rawSteps.length > 1;

        // Directly use expressions which are not path expression
        if (!requireSorting && steps.length === 1) {
                return steps[0];
        }

        // We do not have to sort the result of steps expressions when
        // they already result to a ordered set
        if (
                !isAbsolute &&
                steps.length === 1 &&
                steps[0].expectedResultOrder === RESULT_ORDERINGS.SORTED
        ) {
                return steps[0];
        }

        if (isAbsolute && steps.length === 0) {
                return new AbsolutePathExpression(null);
        }
        const pathExpression = new PathExpression(steps, requireSorting);
        if (isAbsolute) {
                return new AbsolutePathExpression(pathExpression);
        }
        return pathExpression;
}

function piTest(ast: IAST, _compilationOptions: CompilationOptions) {
        const piTarget = astHelper.getFirstChild(ast, 'piTarget');
        if (piTarget) {
                return new PITest(astHelper.getTextContent(piTarget));
        }
        return new KindTest(7);
}

function commentTest(_ast: IAST, _compilationOptions: CompilationOptions) {
        return new KindTest(8);
}

function documentTest(_ast: IAST, _compilationOptions: CompilationOptions) {
        return new KindTest(9);
}

function elementTest(ast: IAST, _compilationOptions: CompilationOptions) {
        const elementName = astHelper.getFirstChild(ast, 'elementName');
        const star = elementName && astHelper.getFirstChild(elementName, 'star');
        if (!elementName || star) {
                return new KindTest(1);
        }
        return new NameTest(astHelper.getQName(astHelper.getFirstChild(elementName, 'QName')), {
                kind: 1,
        });
}

function attributeTest(ast: IAST, _compilationOptions: CompilationOptions) {
        const attributeName = astHelper.getFirstChild(ast, 'attributeName');
        const star = attributeName && astHelper.getFirstChild(attributeName, 'star');
        if (!attributeName || star) {
                return new KindTest(2);
        }
        return new NameTest(astHelper.getQName(astHelper.getFirstChild(attributeName, 'QName')), {
                kind: 2,
        });
}

function textTest(_ast: IAST, _compilationOptions: CompilationOptions) {
        return new KindTest(3);
}

function quantified(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        const quantifier = astHelper.getTextContent(astHelper.getFirstChild(ast, 'quantifier'));
        const predicateExpr = astHelper.followPath(ast, ['predicateExpr', '*']);
        const quantifierInClauses = astHelper
                .getChildren(ast, 'quantifiedExprInClause')
                .map((inClause) => {
                        const name = astHelper.getQName(
                                astHelper.followPath(inClause, ['typedVariableBinding', 'varName']),
                        );
                        const sourceExpr = astHelper.followPath(inClause, ['sourceExpr', '*']);

                        return { name, sourceExpr: compile(sourceExpr, disallowUpdating(compilationOptions)) };
                });

        return new QuantifiedExpression(
                quantifier,
                quantifierInClauses,
                compile(predicateExpr, disallowUpdating(compilationOptions)),
                type,
        );
}

function sequence(ast: IAST, compilationOptions: CompilationOptions) {
        const childExpressions = astHelper
                .getChildren(ast, '*')
                .map((arg) => compile(arg, compilationOptions));
        if (childExpressions.length === 1) {
                return childExpressions[0];
        }

        const type = astHelper.getAttribute(ast, 'type');
        return new SequenceOperator(
                astHelper.getChildren(ast, '*').map((arg) => compile(arg, compilationOptions)),
                type,
        );
}

function simpleMap(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        return astHelper.getChildren(ast, '*').reduce((lhs: Expression, rhs: IAST) => {
                if (lhs === null) {
                        return compile(rhs, disallowUpdating(compilationOptions));
                }
                return new SimpleMapOperator(lhs, compile(rhs, disallowUpdating(compilationOptions)), type);
        }, null);
}

function stringConcatenateOp(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        const args = [
                astHelper.followPath(ast, ['firstOperand', '*']),
                astHelper.followPath(ast, ['secondOperand', '*']),
        ];
        return new FunctionCall(
                new NamedFunctionRef(
                        {
                                localName: 'concat',
                                namespaceURI: 'http://www.w3.org/2005/xpath-functions',
                                prefix: '',
                        },
                        args.length,
                        type,
                ),
                args.map((arg) => compile(arg, disallowUpdating(compilationOptions))),
                type,
        );
}

function rangeSequenceExpr(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        const args = [
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'startExpr'), '*') as IAST,
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'endExpr'), '*') as IAST,
        ];

        const ref = new NamedFunctionRef(
                {
                        localName: 'to',
                        namespaceURI: 'http://fontoxpath/operators',
                        prefix: '',
                },
                args.length,
                type,
        );

        return new FunctionCall(
                ref,
                args.map((arg) => compile(arg, disallowUpdating(compilationOptions))),
                type,
        );
}

function typeTest(ast: IAST, _compilationOptions: CompilationOptions) {
        const type = astHelper.getQName(ast);
        return new TypeTest(type);
}

function anyMapTest(_ast: IAST, _compilationOptions: CompilationOptions) {
        return new TypeTest({ prefix: '', namespaceURI: null, localName: 'map(*)' });
}

function anyArrayTest(_ast: IAST, _compilationOptions: CompilationOptions) {
        return new TypeTest({ prefix: '', namespaceURI: null, localName: 'array(*)' });
}

function unaryPlus(
        ast: IAST,
        compilationOptions: { allowUpdating?: boolean; allowXQuery?: boolean },
) {
        const operand = astHelper.getFirstChild(astHelper.getFirstChild(ast, 'operand'), '*');
        const type = astHelper.getAttribute(ast, 'type');
        return new Unary('+', compile(operand, compilationOptions), type);
}

function unaryMinus(
        ast: IAST,
        compilationOptions: { allowUpdating?: boolean; allowXQuery?: boolean },
) {
        const operand = astHelper.getFirstChild(astHelper.getFirstChild(ast, 'operand'), '*');
        const type = astHelper.getAttribute(ast, 'type');
        return new Unary('-', compile(operand, compilationOptions), type);
}

function unionOp(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        return new Union(
                [
                        compile(
                                astHelper.followPath(ast, ['firstOperand', '*']),
                                disallowUpdating(compilationOptions),
                        ),
                        compile(
                                astHelper.followPath(ast, ['secondOperand', '*']),
                                disallowUpdating(compilationOptions),
                        ),
                ],
                type,
        );
}

function intersectExcept(ast: IAST, compilationOptions: CompilationOptions) {
        const type = astHelper.getAttribute(ast, 'type');
        return new IntersectExcept(
                ast[0],
                compile(
                        astHelper.followPath(ast, ['firstOperand', '*']),
                        disallowUpdating(compilationOptions),
                ),
                compile(
                        astHelper.followPath(ast, ['secondOperand', '*']),
                        disallowUpdating(compilationOptions),
                ),
                type,
        );
}

function varRef(ast: IAST, _compilationOptions: CompilationOptions) {
        const { prefix, namespaceURI, localName } = astHelper.getQName(
                astHelper.getFirstChild(ast, 'name'),
        );
        return new VarRef(prefix, namespaceURI, localName);
}

function wildcard(ast: IAST, _compilationOptions: CompilationOptions) {
        if (!astHelper.getFirstChild(ast, 'star')) {
                return new NameTest({
                        localName: '*',
                        namespaceURI: null,
                        prefix: '*',
                });
        }
        const uri = astHelper.getFirstChild(ast, 'uri');
        if (uri) {
                return new NameTest({
                        localName: '*',
                        namespaceURI: astHelper.getTextContent(uri),
                        prefix: '',
                });
        }

        // Either the prefix or the localName are 'starred', find out which one
        const ncName = astHelper.getFirstChild(ast, 'NCName');
        if (astHelper.getFirstChild(ast, '*')[0] === 'star') {
                // The prefix is 'starred'
                return new NameTest({
                        localName: astHelper.getTextContent(ncName),
                        namespaceURI: null,
                        prefix: '*',
                });
        }

        // The localName is 'starred'
        return new NameTest({
                localName: '*',
                namespaceURI: null,
                prefix: astHelper.getTextContent(ncName),
        });
}

// XQuery Node constructors
function dirElementConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        if (!compilationOptions.allowXQuery) {
                throw new Error('XPST0003: Use of XQuery functionality is not allowed in XPath context');
        }
        const name = astHelper.getQName(astHelper.getFirstChild(ast, 'tagName'));

        const attList = astHelper.getFirstChild(ast, 'attributeList');
        const attributes = attList
                ? astHelper
                                .getChildren(attList, 'attributeConstructor')
                                .map((attr) => compile(attr, disallowUpdating(compilationOptions)))
                : [];

        const namespaceDecls = attList
                ? astHelper.getChildren(attList, 'namespaceDeclaration').map((namespaceDecl) => {
                                const prefixElement = astHelper.getFirstChild(namespaceDecl, 'prefix');
                                return {
                                        prefix: prefixElement ? astHelper.getTextContent(prefixElement) : '',
                                        uri: astHelper.getTextContent(astHelper.getFirstChild(namespaceDecl, 'uri')),
                                };
                  })
                : [];

        const content = astHelper.getFirstChild(ast, 'elementContent');
        const contentExpressions = content
                ? astHelper
                                .getChildren(content, '*')
                                .map((child) => compile(child, disallowUpdating(compilationOptions)))
                : [];

        return new ElementConstructor(
                name,
                attributes as AttributeConstructor[],
                namespaceDecls,
                contentExpressions,
        );
}

function CDataSection(ast: IAST, _compilationOptions: CompilationOptions) {
        // Walks like a stringliteral, talks like a stringliteral, it's a stringliteral
        return new Literal(astHelper.getTextContent(ast), {
                type: ValueType.XSSTRING,
                mult: SequenceMultiplicity.EXACTLY_ONE,
        });
}

function attributeConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        if (!compilationOptions.allowXQuery) {
                throw new Error('XPST0003: Use of XQuery functionality is not allowed in XPath context');
        }
        const attrName = astHelper.getQName(astHelper.getFirstChild(ast, 'attributeName'));
        const attrValueElement = astHelper.getFirstChild(ast, 'attributeValue');
        const attrValue = attrValueElement ? astHelper.getTextContent(attrValueElement) : null;
        const attrValueExprElement = astHelper.getFirstChild(ast, 'attributeValueExpr');
        const attrValueExpressions = attrValueExprElement
                ? astHelper
                                .getChildren(attrValueExprElement, '*')
                                .map((expr) => compile(expr, disallowUpdating(compilationOptions)))
                : null;
        return new AttributeConstructor(attrName, {
                value: attrValue,
                valueExprParts: attrValueExpressions,
        });
}

function computedAttributeConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        const tagName = astHelper.getFirstChild(ast, 'tagName');
        let name: { expr: Expression } | { localName: string; namespaceURI: string; prefix: string };
        if (tagName) {
                name = astHelper.getQName(tagName);
        } else {
                const tagNameExpr = astHelper.getFirstChild(ast, 'tagNameExpr');
                name = {
                        expr: compile(
                                astHelper.getFirstChild(tagNameExpr, '*'),
                                disallowUpdating(compilationOptions),
                        ),
                };
        }

        const valueExpr = compile(
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'valueExpr'), '*'),
                disallowUpdating(compilationOptions),
        );

        return new AttributeConstructor(name, {
                valueExprParts: [valueExpr],
        });
}

function computedCommentConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        if (!compilationOptions.allowXQuery) {
                throw new Error('XPST0003: Use of XQuery functionality is not allowed in XPath context');
        }
        const argExpr = astHelper.getFirstChild(ast, 'argExpr');
        const expr = argExpr
                ? compile(astHelper.getFirstChild(argExpr, '*'), disallowUpdating(compilationOptions))
                : null;
        return new CommentConstructor(expr);
}

function computedTextConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        if (!compilationOptions.allowXQuery) {
                throw new Error('XPST0003: Use of XQuery functionality is not allowed in XPath context');
        }
        const argExpr = astHelper.getFirstChild(ast, 'argExpr');
        const expr = argExpr
                ? compile(astHelper.getFirstChild(argExpr, '*'), disallowUpdating(compilationOptions))
                : null;
        return new TextConstructor(expr);
}

function computedElementConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        const tagName = astHelper.getFirstChild(ast, 'tagName');
        let name: { expr: Expression } | { localName: string; namespaceURI: string; prefix: string };
        if (tagName) {
                name = astHelper.getQName(tagName);
        } else {
                const tagNameExpr = astHelper.getFirstChild(ast, 'tagNameExpr');
                name = {
                        expr: compile(
                                astHelper.getFirstChild(tagNameExpr, '*'),
                                disallowUpdating(compilationOptions),
                        ),
                };
        }

        const content = astHelper.getFirstChild(ast, 'contentExpr');
        const contentExpressions = content
                ? astHelper
                                .getChildren(content, '*')
                                .map((child) => compile(child, disallowUpdating(compilationOptions)))
                : [];

        return new ElementConstructor(name, [], [], contentExpressions);
}

function computedPIConstructor(ast: IAST, compilationOptions: CompilationOptions) {
        if (!compilationOptions.allowXQuery) {
                throw new Error('XPST0003: Use of XQuery functionality is not allowed in XPath context');
        }

        const targetExpr = astHelper.getFirstChild(ast, 'piTargetExpr');
        const target = astHelper.getFirstChild(ast, 'piTarget');
        const piValueExpr = astHelper.getFirstChild(ast, 'piValueExpr');
        const type = astHelper.getAttribute(ast, 'type');

        return new PIConstructor(
                {
                        targetExpr: targetExpr
                                ? compile(
                                                astHelper.getFirstChild(targetExpr, '*'),
                                                disallowUpdating(compilationOptions),
                                  )
                                : null,
                        targetValue: target ? astHelper.getTextContent(target) : null,
                },
                piValueExpr
                        ? compile(
                                        astHelper.getFirstChild(piValueExpr, '*'),
                                        disallowUpdating(compilationOptions),
                          )
                        : new SequenceOperator([], type),
        );
}

function deleteExpression(
        ast: IAST,
        compilationOptions: { allowUpdating?: boolean; allowXQuery?: boolean },
) {
        const targetExpr = compile(astHelper.followPath(ast, ['targetExpr', '*']), compilationOptions);
        return new DeleteExpression(targetExpr);
}

function insertExpression(ast: IAST, compilationOptions: CompilationOptions) {
        const sourceExpr = compile(astHelper.followPath(ast, ['sourceExpr', '*']), compilationOptions);
        let targetChoice: TargetChoice;
        const insertTargetChoice = astHelper.getChildren(ast, '*')[1];
        switch (insertTargetChoice[0]) {
                case 'insertAfter':
                        targetChoice = TargetChoice.INSERT_AFTER;
                        break;
                case 'insertBefore':
                        targetChoice = TargetChoice.INSERT_BEFORE;
                        break;
                case 'insertInto': {
                        const insertAfterChoice = astHelper.getFirstChild(insertTargetChoice, '*');
                        if (insertAfterChoice) {
                                targetChoice =
                                        insertAfterChoice[0] === 'insertAsFirst'
                                                ? TargetChoice.INSERT_INTO_AS_FIRST
                                                : TargetChoice.INSERT_INTO_AS_LAST;
                        } else {
                                targetChoice = TargetChoice.INSERT_INTO;
                        }
                        break;
                }
        }
        const targetExpr = compile(astHelper.followPath(ast, ['targetExpr', '*']), compilationOptions);
        return new InsertExpression(sourceExpr, targetChoice, targetExpr);
}

function renameExpression(ast: IAST, compilationOptions: CompilationOptions) {
        const targetExpr = compile(astHelper.followPath(ast, ['targetExpr', '*']), compilationOptions);
        const newNameExpr = compile(
                astHelper.followPath(ast, ['newNameExpr', '*']),
                compilationOptions,
        );
        return new RenameExpression(targetExpr, newNameExpr);
}

function replaceExpression(ast: IAST, compilationOptions: CompilationOptions) {
        const isReplaceValue = !!astHelper.getFirstChild(ast, 'replaceValue');
        const targetExpr = compile(astHelper.followPath(ast, ['targetExpr', '*']), compilationOptions);
        const replacementExpr = compile(
                astHelper.followPath(ast, ['replacementExpr', '*']),
                compilationOptions,
        );
        return new ReplaceExpression(isReplaceValue, targetExpr, replacementExpr);
}

function transformExpression(ast: IAST, compilationOptions: CompilationOptions) {
        const transformCopies = astHelper
                .getChildren(astHelper.getFirstChild(ast, 'transformCopies'), 'transformCopy')
                .map((transformCopy) => {
                        const varName = astHelper.getQName(
                                astHelper.getFirstChild(astHelper.getFirstChild(transformCopy, 'varRef'), 'name'),
                        );
                        const sourceExpr = compile(
                                astHelper.getFirstChild(astHelper.getFirstChild(transformCopy, 'copySource'), '*'),
                                compilationOptions,
                        );
                        return {
                                sourceExpr,
                                varRef: new QName(varName.prefix, varName.namespaceURI, varName.localName),
                        };
                });
        const modifyExpr = compile(
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'modifyExpr'), '*'),
                compilationOptions,
        );
        const returnExpr = compile(
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'returnExpr'), '*'),
                compilationOptions,
        );
        return new TransformExpression(transformCopies, modifyExpr, returnExpr);
}

function typeswitchExpr(ast: IAST, compilationOptions: CompilationOptions) {
        if (!compilationOptions.allowXQuery) {
                throw new Error('XPST0003: Use of XQuery functionality is not allowed in XPath context');
        }

        const type = astHelper.getAttribute(ast, 'type');

        const argExpr = compile(
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'argExpr'), '*'),
                compilationOptions,
        );

        const caseClause = astHelper.getChildren(ast, 'typeswitchExprCaseClause');

        const caseClauseExpressions = caseClause.map((caseClauseExpression) => {
                const caseNodes: IAST[] =
                        astHelper.getChildren(caseClauseExpression, 'sequenceTypeUnion').length === 0
                                ? [astHelper.getFirstChild(caseClauseExpression, 'sequenceType')]
                                : astHelper.getChildren(
                                                astHelper.getFirstChild(caseClauseExpression, 'sequenceTypeUnion'),
                                                'sequenceType',
                                  );

                const resultExpression = compile(
                        astHelper.followPath(caseClauseExpression, ['resultExpr', '*']),
                        compilationOptions,
                ) as PossiblyUpdatingExpression;

                return {
                        caseClauseExpression: resultExpression,
                        typeTests: caseNodes.map((sequenceTypeAstNode: IAST) => {
                                const occurrenceIndicator = astHelper.getFirstChild(
                                        sequenceTypeAstNode,
                                        'occurrenceIndicator',
                                );
                                return {
                                        occurrenceIndicator: (occurrenceIndicator
                                                ? astHelper.getTextContent(occurrenceIndicator)
                                                : '') as '*' | '?' | '+' | '',
                                        typeTest: compile(
                                                astHelper.getFirstChild(sequenceTypeAstNode, '*'),
                                                compilationOptions,
                                        ),
                                };
                        }),
                };
        });

        const defaultExpression = compile(
                astHelper.followPath(ast, ['typeswitchExprDefaultClause', 'resultExpr', '*']),
                compilationOptions,
        ) as PossiblyUpdatingExpression;

        return new TypeSwitchExpression(argExpr, caseClauseExpressions, defaultExpression, type);
}

function switchExpr(ast: IAST, compilationOptions: CompilationOptions) {
        if (!compilationOptions.allowXQuery) {
                throw new Error('XPST0003: Use of XQuery functionality is not allowed in XPath context');
        }

        const type = astHelper.getAttribute(ast, 'type');

        const argExpr = compile(
                astHelper.getFirstChild(astHelper.getFirstChild(ast, 'argExpr'), '*'),
                compilationOptions,
        );

        const caseClauses = astHelper.getChildren(ast, 'switchExprCaseClause');

        const caseClauseExpressions = caseClauses.map((caseClauseExpression) => {
                const caseNodes: IAST[] = astHelper.getChildren(caseClauseExpression, 'switchCaseExpr');

                const resultExpression = compile(
                        astHelper.followPath(caseClauseExpression, ['resultExpr', '*']),
                        compilationOptions,
                ) as PossiblyUpdatingExpression;

                return {
                        caseClauseExpression: resultExpression,
                        tests: caseNodes.map((caseNode) =>
                                compile(astHelper.getFirstChild(caseNode, '*'), compilationOptions),
                        ),
                };
        });

        const defaultExpression = compile(
                astHelper.followPath(ast, ['switchExprDefaultClause', 'resultExpr', '*']),
                compilationOptions,
        ) as PossiblyUpdatingExpression;

        return new SwitchExpression(argExpr, caseClauseExpressions, defaultExpression, type);
}

export default function (xPathAst: IAST, compilationOptions: CompilationOptions): Expression {
        return compile(xPathAst, compilationOptions);
}

FontoXML / fontoxpath / 6942291632

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