1 // Copyright 2014 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
9 // The constant is known to the compiler.
10 // There is no fundamental theory behind this number.
11 const tmpStringBufSize = 32
13 type tmpBuf [tmpStringBufSize]byte
15 // concatstrings implements a Go string concatenation x+y+z+...
16 // The operands are passed in the slice a.
17 // If buf != nil, the compiler has determined that the result does not
18 // escape the calling function, so the string data can be stored in buf
20 func concatstrings(buf *tmpBuf, a []string) string {
30 throw("string concatenation too long")
40 // If there is just one string and either it is not on the stack
41 // or our result does not escape the calling frame (buf != nil),
42 // then we can return that string directly.
43 if count == 1 && (buf != nil || !stringDataOnStack(a[idx])) {
46 s, b := rawstringtmp(buf, l)
54 func concatstring2(buf *tmpBuf, a [2]string) string {
55 return concatstrings(buf, a[:])
58 func concatstring3(buf *tmpBuf, a [3]string) string {
59 return concatstrings(buf, a[:])
62 func concatstring4(buf *tmpBuf, a [4]string) string {
63 return concatstrings(buf, a[:])
66 func concatstring5(buf *tmpBuf, a [5]string) string {
67 return concatstrings(buf, a[:])
70 // Buf is a fixed-size buffer for the result,
71 // it is not nil if the result does not escape.
72 func slicebytetostring(buf *tmpBuf, b []byte) (str string) {
75 // Turns out to be a relatively common case.
76 // Consider that you want to parse out data between parens in "foo()bar",
77 // you find the indices and convert the subslice to string.
81 racereadrangepc(unsafe.Pointer(&b[0]),
84 funcPC(slicebytetostring))
87 msanread(unsafe.Pointer(&b[0]), uintptr(l))
90 stringStructOf(&str).str = unsafe.Pointer(&staticbytes[b[0]])
91 stringStructOf(&str).len = 1
96 if buf != nil && len(b) <= len(buf) {
97 p = unsafe.Pointer(buf)
99 p = mallocgc(uintptr(len(b)), nil, false)
101 stringStructOf(&str).str = p
102 stringStructOf(&str).len = len(b)
103 memmove(p, (*(*slice)(unsafe.Pointer(&b))).array, uintptr(len(b)))
107 // stringDataOnStack reports whether the string's data is
108 // stored on the current goroutine's stack.
109 func stringDataOnStack(s string) bool {
110 ptr := uintptr(stringStructOf(&s).str)
112 return stk.lo <= ptr && ptr < stk.hi
115 func rawstringtmp(buf *tmpBuf, l int) (s string, b []byte) {
116 if buf != nil && l <= len(buf) {
118 s = slicebytetostringtmp(b)
125 // slicebytetostringtmp returns a "string" referring to the actual []byte bytes.
127 // Callers need to ensure that the returned string will not be used after
128 // the calling goroutine modifies the original slice or synchronizes with
129 // another goroutine.
131 // The function is only called when instrumenting
132 // and otherwise intrinsified by the compiler.
134 // Some internal compiler optimizations use this function.
135 // - Used for m[string(k)] lookup where m is a string-keyed map and k is a []byte.
136 // - Used for "<"+string(b)+">" concatenation where b is []byte.
137 // - Used for string(b)=="foo" comparison where b is []byte.
138 func slicebytetostringtmp(b []byte) string {
139 if raceenabled && len(b) > 0 {
140 racereadrangepc(unsafe.Pointer(&b[0]),
143 funcPC(slicebytetostringtmp))
145 if msanenabled && len(b) > 0 {
146 msanread(unsafe.Pointer(&b[0]), uintptr(len(b)))
148 return *(*string)(unsafe.Pointer(&b))
151 func stringtoslicebyte(buf *tmpBuf, s string) []byte {
153 if buf != nil && len(s) <= len(buf) {
157 b = rawbyteslice(len(s))
163 func stringtoslicerune(buf *[tmpStringBufSize]rune, s string) []rune {
165 // unlike slicerunetostring, no race because strings are immutable.
172 if buf != nil && n <= len(buf) {
173 *buf = [tmpStringBufSize]rune{}
180 for _, r := range s {
187 func slicerunetostring(buf *tmpBuf, a []rune) string {
188 if raceenabled && len(a) > 0 {
189 racereadrangepc(unsafe.Pointer(&a[0]),
190 uintptr(len(a))*unsafe.Sizeof(a[0]),
192 funcPC(slicerunetostring))
194 if msanenabled && len(a) > 0 {
195 msanread(unsafe.Pointer(&a[0]), uintptr(len(a))*unsafe.Sizeof(a[0]))
199 for _, r := range a {
200 size1 += encoderune(dum[:], r)
202 s, b := rawstringtmp(buf, size1+3)
204 for _, r := range a {
209 size2 += encoderune(b[size2:], r)
214 type stringStruct struct {
219 // Variant with *byte pointer type for DWARF debugging.
220 type stringStructDWARF struct {
225 func stringStructOf(sp *string) *stringStruct {
226 return (*stringStruct)(unsafe.Pointer(sp))
229 func intstring(buf *[4]byte, v int64) string {
234 s = slicebytetostringtmp(b)
238 if int64(rune(v)) != v {
241 n := encoderune(b, rune(v))
245 // rawstring allocates storage for a new string. The returned
246 // string and byte slice both refer to the same storage.
247 // The storage is not zeroed. Callers should use
248 // b to set the string contents and then drop b.
249 func rawstring(size int) (s string, b []byte) {
250 p := mallocgc(uintptr(size), nil, false)
252 stringStructOf(&s).str = p
253 stringStructOf(&s).len = size
255 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, size}
260 // rawbyteslice allocates a new byte slice. The byte slice is not zeroed.
261 func rawbyteslice(size int) (b []byte) {
262 cap := roundupsize(uintptr(size))
263 p := mallocgc(cap, nil, false)
264 if cap != uintptr(size) {
265 memclrNoHeapPointers(add(p, uintptr(size)), cap-uintptr(size))
268 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(cap)}
272 // rawruneslice allocates a new rune slice. The rune slice is not zeroed.
273 func rawruneslice(size int) (b []rune) {
274 if uintptr(size) > maxAlloc/4 {
275 throw("out of memory")
277 mem := roundupsize(uintptr(size) * 4)
278 p := mallocgc(mem, nil, false)
279 if mem != uintptr(size)*4 {
280 memclrNoHeapPointers(add(p, uintptr(size)*4), mem-uintptr(size)*4)
283 *(*slice)(unsafe.Pointer(&b)) = slice{p, size, int(mem / 4)}
288 func gobytes(p *byte, n int) (b []byte) {
290 return make([]byte, 0)
293 if n < 0 || uintptr(n) > maxAlloc {
294 panic(errorString("gobytes: length out of range"))
297 bp := mallocgc(uintptr(n), nil, false)
298 memmove(bp, unsafe.Pointer(p), uintptr(n))
300 *(*slice)(unsafe.Pointer(&b)) = slice{bp, n, n}
304 func gostring(p *byte) string {
310 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
314 func gostringn(p *byte, l int) string {
319 memmove(unsafe.Pointer(&b[0]), unsafe.Pointer(p), uintptr(l))
323 func index(s, t string) int {
327 for i := 0; i < len(s); i++ {
328 if s[i] == t[0] && hasprefix(s[i:], t) {
335 func contains(s, t string) bool {
336 return index(s, t) >= 0
339 func hasprefix(s, t string) bool {
340 return len(s) >= len(t) && s[:len(t)] == t
345 maxInt = int(maxUint >> 1)
348 // atoi parses an int from a string s.
349 // The bool result reports whether s is a number
350 // representable by a value of type int.
351 func atoi(s string) (int, bool) {
363 for i := 0; i < len(s); i++ {
365 if c < '0' || c > '9' {
373 un1 := un + uint(c) - '0'
381 if !neg && un > uint(maxInt) {
384 if neg && un > uint(maxInt)+1 {
396 // atoi32 is like atoi but for integers
397 // that fit into an int32.
398 func atoi32(s string) (int32, bool) {
399 if n, ok := atoi(s); n == int(int32(n)) {
406 func findnull(s *byte) int {
410 p := (*[maxAlloc/2 - 1]byte)(unsafe.Pointer(s))
418 func findnullw(s *uint16) int {
422 p := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(s))
431 func gostringnocopy(str *byte) string {
432 ss := stringStruct{str: unsafe.Pointer(str), len: findnull(str)}
433 s := *(*string)(unsafe.Pointer(&ss))
437 func gostringw(strw *uint16) string {
439 str := (*[maxAlloc/2/2 - 1]uint16)(unsafe.Pointer(strw))
441 for i := 0; str[i] != 0; i++ {
442 n1 += encoderune(buf[:], rune(str[i]))
444 s, b := rawstring(n1 + 4)
446 for i := 0; str[i] != 0; i++ {
451 n2 += encoderune(b[n2:], rune(str[i]))
453 b[n2] = 0 // for luck