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JuliaLang / julia / #37430

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#37430

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Use `sum` in `count` for constant folding of type based predicates (#48454)

* Use `sum` in `count` for constant folding for type based predicates.

* Use existing `_bool` functionality for type assertion

---------

Co-authored-by: Sukera <Seelengrab@users.noreply.github.com>

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98.59
/base/strings/string.jl
1
# This file is a part of Julia. License is MIT: https://julialang.org/license
2

3
"""
4
    StringIndexError(str, i)
5

6
An error occurred when trying to access `str` at index `i` that is not valid.
7
"""
8
struct StringIndexError <: Exception
9
    string::AbstractString
747✔
10
    index::Integer
11
end
12
@noinline string_index_err(s::AbstractString, i::Integer) =
743✔
13
    throw(StringIndexError(s, Int(i)))
14
function Base.showerror(io::IO, exc::StringIndexError)
4✔
15
    s = exc.string
4✔
16
    print(io, "StringIndexError: ", "invalid index [$(exc.index)]")
4✔
17
    if firstindex(s) <= exc.index <= ncodeunits(s)
4✔
18
        iprev = thisind(s, exc.index)
4✔
19
        inext = nextind(s, iprev)
4✔
20
        escprev = escape_string(s[iprev:iprev])
4✔
21
        if inext <= ncodeunits(s)
4✔
22
            escnext = escape_string(s[inext:inext])
3✔
23
            print(io, ", valid nearby indices [$iprev]=>'$escprev', [$inext]=>'$escnext'")
3✔
24
        else
25
            print(io, ", valid nearby index [$iprev]=>'$escprev'")
1✔
26
        end
27
    end
28
end
29

30
const ByteArray = Union{CodeUnits{UInt8,String}, Vector{UInt8},Vector{Int8}, FastContiguousSubArray{UInt8,1,CodeUnits{UInt8,String}}, FastContiguousSubArray{UInt8,1,Vector{UInt8}}, FastContiguousSubArray{Int8,1,Vector{Int8}}}
31

32
@inline between(b::T, lo::T, hi::T) where {T<:Integer} = (lo ≤ b) & (b ≤ hi)
146,431,323✔
33

34
"""
35
    String <: AbstractString
36

37
The default string type in Julia, used by e.g. string literals.
38

39
`String`s are immutable sequences of `Char`s. A `String` is stored internally as
40
a contiguous byte array, and while they are interpreted as being UTF-8 encoded,
41
they can be composed of any byte sequence. Use [`isvalid`](@ref) to validate
42
that the underlying byte sequence is valid as UTF-8.
43
"""
44
String
45

46
## constructors and conversions ##
47

48
# String constructor docstring from boot.jl, workaround for #16730
49
# and the unavailability of @doc in boot.jl context.
50
"""
51
    String(v::AbstractVector{UInt8})
52

53
Create a new `String` object using the data buffer from byte vector `v`.
54
If `v` is a `Vector{UInt8}` it will be truncated to zero length and future
55
modification of `v` cannot affect the contents of the resulting string.
56
To avoid truncation of `Vector{UInt8}` data, use `String(copy(v))`; for other
57
`AbstractVector` types, `String(v)` already makes a copy.
58

59
When possible, the memory of `v` will be used without copying when the `String`
60
object is created. This is guaranteed to be the case for byte vectors returned
61
by [`take!`](@ref) on a writable [`IOBuffer`](@ref) and by calls to
62
[`read(io, nb)`](@ref). This allows zero-copy conversion of I/O data to strings.
63
In other cases, `Vector{UInt8}` data may be copied, but `v` is truncated anyway
64
to guarantee consistent behavior.
65
"""
66
String(v::AbstractVector{UInt8}) = String(copyto!(StringVector(length(v)), v))
2,612,856✔
67
String(v::Vector{UInt8}) = ccall(:jl_array_to_string, Ref{String}, (Any,), v)
6,155,809✔
68

69
"""
70
    unsafe_string(p::Ptr{UInt8}, [length::Integer])
71

72
Copy a string from the address of a C-style (NUL-terminated) string encoded as UTF-8.
73
(The pointer can be safely freed afterwards.) If `length` is specified
74
(the length of the data in bytes), the string does not have to be NUL-terminated.
75

76
This function is labeled "unsafe" because it will crash if `p` is not
77
a valid memory address to data of the requested length.
78
"""
79
function unsafe_string(p::Union{Ptr{UInt8},Ptr{Int8}}, len::Integer)
1,201✔
80
    p == C_NULL && throw(ArgumentError("cannot convert NULL to string"))
431,753✔
81
    ccall(:jl_pchar_to_string, Ref{String}, (Ptr{UInt8}, Int), p, len)
431,752✔
82
end
83
function unsafe_string(p::Union{Ptr{UInt8},Ptr{Int8}})
21,064✔
84
    p == C_NULL && throw(ArgumentError("cannot convert NULL to string"))
2,735,859✔
85
    ccall(:jl_cstr_to_string, Ref{String}, (Ptr{UInt8},), p)
2,735,858✔
86
end
87

88
# This is @assume_effects :effect_free :nothrow :terminates_globally @ccall jl_alloc_string(n::Csize_t)::Ref{String},
89
# but the macro is not available at this time in bootstrap, so we write it manually.
90
@eval _string_n(n::Integer) = $(Expr(:foreigncall, QuoteNode(:jl_alloc_string), Ref{String}, Expr(:call, Expr(:core, :svec), :Csize_t), 1, QuoteNode((:ccall,0xe)), :(convert(Csize_t, n))))
138,781,739✔
91

92
"""
93
    String(s::AbstractString)
94

95
Create a new `String` from an existing `AbstractString`.
96
"""
97
String(s::AbstractString) = print_to_string(s)
397✔
98
@assume_effects :total String(s::Symbol) = unsafe_string(unsafe_convert(Ptr{UInt8}, s))
406,384✔
99

100
unsafe_wrap(::Type{Vector{UInt8}}, s::String) = ccall(:jl_string_to_array, Ref{Vector{UInt8}}, (Any,), s)
6,374,734✔
101

102
Vector{UInt8}(s::CodeUnits{UInt8,String}) = copyto!(Vector{UInt8}(undef, length(s)), s)
20,525✔
103
Vector{UInt8}(s::String) = Vector{UInt8}(codeunits(s))
20,452✔
104
Array{UInt8}(s::String)  = Vector{UInt8}(codeunits(s))
105

106
String(s::CodeUnits{UInt8,String}) = s.s
4✔
107

108
## low-level functions ##
109

110
pointer(s::String) = unsafe_convert(Ptr{UInt8}, s)
422,482,132✔
111
pointer(s::String, i::Integer) = pointer(s) + Int(i)::Int - 1
270,153,517✔
112

113
ncodeunits(s::String) = Core.sizeof(s)
277,729,603✔
114
codeunit(s::String) = UInt8
115

116
@inline function codeunit(s::String, i::Integer)
1,039,154✔
117
    @boundscheck checkbounds(s, i)
252,129,094✔
118
    b = GC.@preserve s unsafe_load(pointer(s, i))
252,129,094✔
119
    return b
252,129,094✔
120
end
121

122
## comparison ##
123

124
_memcmp(a::Union{Ptr{UInt8},AbstractString}, b::Union{Ptr{UInt8},AbstractString}, len) =
4,100,534✔
125
    ccall(:memcmp, Cint, (Ptr{UInt8}, Ptr{UInt8}, Csize_t), a, b, len % Csize_t) % Int
126

127
function cmp(a::String, b::String)
1✔
128
    al, bl = sizeof(a), sizeof(b)
287,000✔
129
    c = _memcmp(a, b, min(al,bl))
287,000✔
130
    return c < 0 ? -1 : c > 0 ? +1 : cmp(al,bl)
436,975✔
131
end
132

133
function ==(a::String, b::String)
3,999,196✔
134
    pointer_from_objref(a) == pointer_from_objref(b) && return true
3,999,196✔
135
    al = sizeof(a)
3,933,405✔
136
    return al == sizeof(b) && 0 == _memcmp(a, b, al)
3,933,405✔
137
end
138

139
typemin(::Type{String}) = ""
2✔
140
typemin(::String) = typemin(String)
1✔
141

142
## thisind, nextind ##
143

144
@propagate_inbounds thisind(s::String, i::Int) = _thisind_str(s, i)
173,309,399✔
145

146
# s should be String or SubString{String}
147
@inline function _thisind_str(s, i::Int)
×
148
    i == 0 && return 0
87,312,220✔
149
    n = ncodeunits(s)
87,292,597✔
150
    i == n + 1 && return i
87,292,597✔
151
    @boundscheck between(i, 1, n) || throw(BoundsError(s, i))
87,270,155✔
152
    @inbounds b = codeunit(s, i)
87,270,131✔
153
    (b & 0xc0 == 0x80) & (i-1 > 0) || return i
154,473,482✔
154
    @inbounds b = codeunit(s, i-1)
20,066,780✔
155
    between(b, 0b11000000, 0b11110111) && return i-1
20,066,780✔
156
    (b & 0xc0 == 0x80) & (i-2 > 0) || return i
15,659,634✔
157
    @inbounds b = codeunit(s, i-2)
7,170,442✔
158
    between(b, 0b11100000, 0b11110111) && return i-2
7,170,442✔
159
    (b & 0xc0 == 0x80) & (i-3 > 0) || return i
5,906,533✔
160
    @inbounds b = codeunit(s, i-3)
1,026,983✔
161
    between(b, 0b11110000, 0b11110111) && return i-3
1,026,983✔
162
    return i
241,004✔
163
end
164

165
@propagate_inbounds nextind(s::String, i::Int) = _nextind_str(s, i)
12,354,256✔
166

167
# s should be String or SubString{String}
168
@inline function _nextind_str(s, i::Int)
12,915,222✔
169
    i == 0 && return 1
12,915,222✔
170
    n = ncodeunits(s)
12,901,387✔
171
    @boundscheck between(i, 1, n) || throw(BoundsError(s, i))
12,901,399✔
172
    @inbounds l = codeunit(s, i)
12,901,375✔
173
    (l < 0x80) | (0xf8 ≤ l) && return i+1
12,901,375✔
174
    if l < 0xc0
131,068✔
175
        i′ = @inbounds thisind(s, i)
50,955✔
176
        return i′ < i ? @inbounds(nextind(s, i′)) : i+1
30,202✔
177
    end
178
    # first continuation byte
179
    (i += 1) > n && return i
100,866✔
180
    @inbounds b = codeunit(s, i)
100,232✔
181
    b & 0xc0 ≠ 0x80 && return i
100,232✔
182
    ((i += 1) > n) | (l < 0xe0) && return i
92,988✔
183
    # second continuation byte
184
    @inbounds b = codeunit(s, i)
75,792✔
185
    b & 0xc0 ≠ 0x80 && return i
75,792✔
186
    ((i += 1) > n) | (l < 0xf0) && return i
72,159✔
187
    # third continuation byte
188
    @inbounds b = codeunit(s, i)
20,729✔
189
    ifelse(b & 0xc0 ≠ 0x80, i, i+1)
20,729✔
190
end
191

192
## checking UTF-8 & ACSII validity ##
193

194
byte_string_classify(s::Union{String,Vector{UInt8},FastContiguousSubArray{UInt8,1,Vector{UInt8}}}) =
20,324✔
195
    ccall(:u8_isvalid, Int32, (Ptr{UInt8}, Int), s, sizeof(s))
196
    # 0: neither valid ASCII nor UTF-8
197
    # 1: valid ASCII
198
    # 2: valid UTF-8
199

200
isvalid(::Type{String}, s::Union{Vector{UInt8},FastContiguousSubArray{UInt8,1,Vector{UInt8}},String}) = byte_string_classify(s) ≠ 0
20,324✔
201
isvalid(s::String) = isvalid(String, s)
41✔
202

203
is_valid_continuation(c) = c & 0xc0 == 0x80
4✔
204

205
## required core functionality ##
206

207
@inline function iterate(s::String, i::Int=firstindex(s))
54,674✔
208
    (i % UInt) - 1 < ncodeunits(s) || return nothing
22,555,877✔
209
    b = @inbounds codeunit(s, i)
15,668,406✔
210
    u = UInt32(b) << 24
15,668,406✔
211
    between(b, 0x80, 0xf7) || return reinterpret(Char, u), i+1
30,505,486✔
212
    return iterate_continued(s, i, u)
831,326✔
213
end
214

215
function iterate_continued(s::String, i::Int, u::UInt32)
831,326✔
216
    u < 0xc0000000 && (i += 1; @goto ret)
831,427✔
217
    n = ncodeunits(s)
831,225✔
218
    # first continuation byte
219
    (i += 1) > n && @goto ret
831,225✔
220
    @inbounds b = codeunit(s, i)
831,205✔
221
    b & 0xc0 == 0x80 || @goto ret
831,205✔
222
    u |= UInt32(b) << 16
831,144✔
223
    # second continuation byte
224
    ((i += 1) > n) | (u < 0xe0000000) && @goto ret
831,144✔
225
    @inbounds b = codeunit(s, i)
802,093✔
226
    b & 0xc0 == 0x80 || @goto ret
802,095✔
227
    u |= UInt32(b) << 8
802,091✔
228
    # third continuation byte
229
    ((i += 1) > n) | (u < 0xf0000000) && @goto ret
802,091✔
230
    @inbounds b = codeunit(s, i)
264,736✔
231
    b & 0xc0 == 0x80 || @goto ret
264,737✔
232
    u |= UInt32(b); i += 1
529,470✔
233
@label ret
×
234
    return reinterpret(Char, u), i
831,326✔
235
end
236

237
@propagate_inbounds function getindex(s::String, i::Int)
151,753✔
238
    b = codeunit(s, i)
2,487,226✔
239
    u = UInt32(b) << 24
2,487,226✔
240
    between(b, 0x80, 0xf7) || return reinterpret(Char, u)
4,971,446✔
241
    return getindex_continued(s, i, u)
3,006✔
242
end
243

244
function getindex_continued(s::String, i::Int, u::UInt32)
3,006✔
245
    if u < 0xc0000000
3,006✔
246
        # called from `getindex` which checks bounds
247
        @inbounds isvalid(s, i) && @goto ret
16✔
248
        string_index_err(s, i)
1✔
249
    end
250
    n = ncodeunits(s)
2,990✔
251

252
    (i += 1) > n && @goto ret
2,990✔
253
    @inbounds b = codeunit(s, i) # cont byte 1
2,989✔
254
    b & 0xc0 == 0x80 || @goto ret
2,989✔
255
    u |= UInt32(b) << 16
2,988✔
256

257
    ((i += 1) > n) | (u < 0xe0000000) && @goto ret
2,988✔
258
    @inbounds b = codeunit(s, i) # cont byte 2
2,001✔
259
    b & 0xc0 == 0x80 || @goto ret
2,001✔
260
    u |= UInt32(b) << 8
2,001✔
261

262
    ((i += 1) > n) | (u < 0xf0000000) && @goto ret
2,001✔
263
    @inbounds b = codeunit(s, i) # cont byte 3
459✔
264
    b & 0xc0 == 0x80 || @goto ret
459✔
265
    u |= UInt32(b)
459✔
266
@label ret
×
267
    return reinterpret(Char, u)
3,005✔
268
end
269

270
getindex(s::String, r::AbstractUnitRange{<:Integer}) = s[Int(first(r)):Int(last(r))]
4✔
271

272
@inline function getindex(s::String, r::UnitRange{Int})
1,498,519✔
273
    isempty(r) && return ""
954,275✔
274
    i, j = first(r), last(r)
84,853✔
275
    @boundscheck begin
931,474✔
276
        checkbounds(s, r)
931,456✔
277
        @inbounds isvalid(s, i) || string_index_err(s, i)
931,444✔
278
        @inbounds isvalid(s, j) || string_index_err(s, j)
931,445✔
279
    end
280
    j = nextind(s, j) - 1
931,467✔
281
    n = j - i + 1
931,467✔
282
    ss = _string_n(n)
931,467✔
283
    GC.@preserve s ss unsafe_copyto!(pointer(ss), pointer(s, i), n)
931,467✔
284
    return ss
931,467✔
285
end
286

287
length(s::String) = length_continued(s, 1, ncodeunits(s), ncodeunits(s))
513,947✔
288

289
@inline function length(s::String, i::Int, j::Int)
68,031✔
290
    @boundscheck begin
191,335✔
291
        0 < i ≤ ncodeunits(s)+1 || throw(BoundsError(s, i))
191,335✔
292
        0 ≤ j < ncodeunits(s)+1 || throw(BoundsError(s, j))
191,339✔
293
    end
294
    j < i && return 0
191,331✔
295
    @inbounds i, k = thisind(s, i), i
283,628✔
296
    c = j - i + (i == k)
141,814✔
297
    length_continued(s, i, j, c)
141,814✔
298
end
299

300
@inline function length_continued(s::String, i::Int, n::Int, c::Int)
886,716✔
301
    i < n || return c
780,066✔
302
    @inbounds b = codeunit(s, i)
531,456✔
303
    @inbounds while true
3,917,502✔
304
        while true
49,978,590✔
305
            (i += 1) ≤ n || return c
50,509,275✔
306
            0xc0 ≤ b ≤ 0xf7 && break
49,447,905✔
307
            b = codeunit(s, i)
46,061,088✔
308
        end
46,061,088✔
309
        l = b
3,386,817✔
310
        b = codeunit(s, i) # cont byte 1
3,386,817✔
311
        c -= (x = b & 0xc0 == 0x80)
3,386,817✔
312
        x & (l ≥ 0xe0) || continue
3,386,817✔
313

314
        (i += 1) ≤ n || return c
3,033,401✔
315
        b = codeunit(s, i) # cont byte 2
3,031,939✔
316
        c -= (x = b & 0xc0 == 0x80)
3,031,939✔
317
        x & (l ≥ 0xf0) || continue
5,177,122✔
318

319
        (i += 1) ≤ n || return c
886,796✔
320
        b = codeunit(s, i) # cont byte 3
886,716✔
321
        c -= (b & 0xc0 == 0x80)
886,716✔
322
    end
3,386,046✔
323
end
324

325
## overload methods for efficiency ##
326

327
isvalid(s::String, i::Int) = checkbounds(Bool, s, i) && thisind(s, i) == i
80,405,587✔
328

329
function isascii(s::String)
25,625✔
330
    @inbounds for i = 1:ncodeunits(s)
51,243✔
331
        codeunit(s, i) >= 0x80 && return false
375,363✔
332
    end
704,784✔
333
    return true
5,301✔
334
end
335

336
"""
337
    repeat(c::AbstractChar, r::Integer) -> String
338

339
Repeat a character `r` times. This can equivalently be accomplished by calling
340
[`c^r`](@ref :^(::Union{AbstractString, AbstractChar}, ::Integer)).
341

342
# Examples
343
```jldoctest
344
julia> repeat('A', 3)
345
"AAA"
346
```
347
"""
348
repeat(c::AbstractChar, r::Integer) = repeat(Char(c), r) # fallback
1✔
349
function repeat(c::Char, r::Integer)
24,711✔
350
    r == 0 && return ""
24,711✔
351
    r < 0 && throw(ArgumentError("can't repeat a character $r times"))
11,887✔
352
    u = bswap(reinterpret(UInt32, c))
11,883✔
353
    n = 4 - (leading_zeros(u | 0xff) >> 3)
11,883✔
354
    s = _string_n(n*r)
11,930✔
355
    p = pointer(s)
11,929✔
356
    GC.@preserve s if n == 1
11,929✔
357
        ccall(:memset, Ptr{Cvoid}, (Ptr{UInt8}, Cint, Csize_t), p, u % UInt8, r)
11,905✔
358
    elseif n == 2
24✔
359
        p16 = reinterpret(Ptr{UInt16}, p)
5✔
360
        for i = 1:r
9✔
361
            unsafe_store!(p16, u % UInt16, i)
14✔
362
        end
19✔
363
    elseif n == 3
19✔
364
        b1 = (u >> 0) % UInt8
15✔
365
        b2 = (u >> 8) % UInt8
15✔
366
        b3 = (u >> 16) % UInt8
15✔
367
        for i = 0:r-1
30✔
368
            unsafe_store!(p, b1, 3i + 1)
37✔
369
            unsafe_store!(p, b2, 3i + 2)
37✔
370
            unsafe_store!(p, b3, 3i + 3)
37✔
371
        end
37✔
372
    elseif n == 4
4✔
373
        p32 = reinterpret(Ptr{UInt32}, p)
4✔
374
        for i = 1:r
8✔
375
            unsafe_store!(p32, u, i)
8✔
376
        end
11,937✔
377
    end
378
    return s
11,882✔
379
end
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