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* Copyright 2006 The Android Open Source Project
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkString_DEFINED
#define SkString_DEFINED
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkTypes.h"
#include "include/private/SkMacros.h"
#include "include/private/SkMalloc.h"
#include "include/private/SkTArray.h"
#include "include/private/SkTo.h"
#include <stdarg.h>
#include <string.h>
#include <atomic>
/* Some helper functions for C strings */
static inline bool SkStrStartsWith(const char string[], const char prefixStr[]) {
return !strncmp(string, prefixStr, strlen(prefixStr));
static inline bool SkStrStartsWith(const char string[], const char prefixChar) {
return (prefixChar == *string);
bool SkStrEndsWith(const char string[], const char suffixStr[]);
bool SkStrEndsWith(const char string[], const char suffixChar);
int SkStrStartsWithOneOf(const char string[], const char prefixes[]);
static inline int SkStrFind(const char string[], const char substring[]) {
const char *first = strstr(string, substring);
if (nullptr == first) return -1;
return SkToInt(first - &string[0]);
static inline int SkStrFindLastOf(const char string[], const char subchar) {
const char* last = strrchr(string, subchar);
if (nullptr == last) return -1;
return SkToInt(last - &string[0]);
static inline bool SkStrContains(const char string[], const char substring[]) {
return (-1 != SkStrFind(string, substring));
static inline bool SkStrContains(const char string[], const char subchar) {
char tmp[2];
tmp[0] = subchar;
tmp[1] = '\0';
return (-1 != SkStrFind(string, tmp));
static inline char *SkStrDup(const char string[]) {
char *ret = (char *) sk_malloc_throw(strlen(string)+1);
return ret;
* The SkStrAppend... methods will write into the provided buffer, assuming it is large enough.
* Each method has an associated const (e.g. SkStrAppendU32_MaxSize) which will be the largest
* value needed for that method's buffer.
* char storage[SkStrAppendU32_MaxSize];
* SkStrAppendU32(storage, value);
* Note : none of the SkStrAppend... methods write a terminating 0 to their buffers. Instead,
* the methods return the ptr to the end of the written part of the buffer. This can be used
* to compute the length, and/or know where to write a 0 if that is desired.
* char storage[SkStrAppendU32_MaxSize + 1];
* char* stop = SkStrAppendU32(storage, value);
* size_t len = stop - storage;
* *stop = 0; // valid, since storage was 1 byte larger than the max.
#define SkStrAppendU32_MaxSize 10
char* SkStrAppendU32(char buffer[], uint32_t);
#define SkStrAppendU64_MaxSize 20
char* SkStrAppendU64(char buffer[], uint64_t, int minDigits);
#define SkStrAppendS32_MaxSize (SkStrAppendU32_MaxSize + 1)
char* SkStrAppendS32(char buffer[], int32_t);
#define SkStrAppendS64_MaxSize (SkStrAppendU64_MaxSize + 1)
char* SkStrAppendS64(char buffer[], int64_t, int minDigits);
* Floats have at most 8 significant digits, so we limit our %g to that.
* However, the total string could be 15 characters: -1.2345678e-005
* In theory we should only expect up to 2 digits for the exponent, but on
* some platforms we have seen 3 (as in the example above).
#define SkStrAppendScalar_MaxSize 15
* Write the scaler in decimal format into buffer, and return a pointer to
* the next char after the last one written. Note: a terminating 0 is not
* written into buffer, which must be at least SkStrAppendScalar_MaxSize.
* Thus if the caller wants to add a 0 at the end, buffer must be at least
* SkStrAppendScalar_MaxSize + 1 bytes large.
#define SkStrAppendScalar SkStrAppendFloat
char* SkStrAppendFloat(char buffer[], float);
/** \class SkString
Light weight class for managing strings. Uses reference
counting to make string assignments and copies very fast
with no extra RAM cost. Assumes UTF8 encoding.
class SK_API SkString {
explicit SkString(size_t len);
explicit SkString(const char text[]);
SkString(const char text[], size_t len);
SkString(const SkString&);
bool isEmpty() const { return 0 == fRec->fLength; }
size_t size() const { return (size_t) fRec->fLength; }
const char* c_str() const { return fRec->data(); }
char operator[](size_t n) const { return this->c_str()[n]; }
bool equals(const SkString&) const;
bool equals(const char text[]) const;
bool equals(const char text[], size_t len) const;
bool startsWith(const char prefixStr[]) const {
return SkStrStartsWith(fRec->data(), prefixStr);
bool startsWith(const char prefixChar) const {
return SkStrStartsWith(fRec->data(), prefixChar);
bool endsWith(const char suffixStr[]) const {
return SkStrEndsWith(fRec->data(), suffixStr);
bool endsWith(const char suffixChar) const {
return SkStrEndsWith(fRec->data(), suffixChar);
bool contains(const char substring[]) const {
return SkStrContains(fRec->data(), substring);
bool contains(const char subchar) const {
return SkStrContains(fRec->data(), subchar);
int find(const char substring[]) const {
return SkStrFind(fRec->data(), substring);
int findLastOf(const char subchar) const {
return SkStrFindLastOf(fRec->data(), subchar);
friend bool operator==(const SkString& a, const SkString& b) {
return a.equals(b);
friend bool operator!=(const SkString& a, const SkString& b) {
return !a.equals(b);
// these methods edit the string
SkString& operator=(const SkString&);
SkString& operator=(SkString&&);
SkString& operator=(const char text[]);
char* writable_str();
char& operator[](size_t n) { return this->writable_str()[n]; }
void reset();
/** Destructive resize, does not preserve contents. */
void resize(size_t len) { this->set(nullptr, len); }
void set(const SkString& src) { *this = src; }
void set(const char text[]);
void set(const char text[], size_t len);
void insert(size_t offset, const SkString& src) { this->insert(offset, src.c_str(), src.size()); }
void insert(size_t offset, const char text[]);
void insert(size_t offset, const char text[], size_t len);
void insertUnichar(size_t offset, SkUnichar);
void insertS32(size_t offset, int32_t value);
void insertS64(size_t offset, int64_t value, int minDigits = 0);
void insertU32(size_t offset, uint32_t value);
void insertU64(size_t offset, uint64_t value, int minDigits = 0);
void insertHex(size_t offset, uint32_t value, int minDigits = 0);
void insertScalar(size_t offset, SkScalar);
void append(const SkString& str) { this->insert((size_t)-1, str); }
void append(const char text[]) { this->insert((size_t)-1, text); }
void append(const char text[], size_t len) { this->insert((size_t)-1, text, len); }
void appendUnichar(SkUnichar uni) { this->insertUnichar((size_t)-1, uni); }
void appendS32(int32_t value) { this->insertS32((size_t)-1, value); }
void appendS64(int64_t value, int minDigits = 0) { this->insertS64((size_t)-1, value, minDigits); }
void appendU32(uint32_t value) { this->insertU32((size_t)-1, value); }
void appendU64(uint64_t value, int minDigits = 0) { this->insertU64((size_t)-1, value, minDigits); }
void appendHex(uint32_t value, int minDigits = 0) { this->insertHex((size_t)-1, value, minDigits); }
void appendScalar(SkScalar value) { this->insertScalar((size_t)-1, value); }
void prepend(const SkString& str) { this->insert(0, str); }
void prepend(const char text[]) { this->insert(0, text); }
void prepend(const char text[], size_t len) { this->insert(0, text, len); }
void prependUnichar(SkUnichar uni) { this->insertUnichar(0, uni); }
void prependS32(int32_t value) { this->insertS32(0, value); }
void prependS64(int32_t value, int minDigits = 0) { this->insertS64(0, value, minDigits); }
void prependHex(uint32_t value, int minDigits = 0) { this->insertHex(0, value, minDigits); }
void prependScalar(SkScalar value) { this->insertScalar((size_t)-1, value); }
void printf(const char format[], ...) SK_PRINTF_LIKE(2, 3);
void appendf(const char format[], ...) SK_PRINTF_LIKE(2, 3);
void appendVAList(const char format[], va_list);
void prependf(const char format[], ...) SK_PRINTF_LIKE(2, 3);
void prependVAList(const char format[], va_list);
void remove(size_t offset, size_t length);
SkString& operator+=(const SkString& s) { this->append(s); return *this; }
SkString& operator+=(const char text[]) { this->append(text); return *this; }
SkString& operator+=(const char c) { this->append(&c, 1); return *this; }
* Swap contents between this and other. This function is guaranteed
* to never fail or throw.
void swap(SkString& other);
struct Rec {
CONSTEXPR Rec(uint32_t len, int32_t refCnt)
: fLength(len), fRefCnt(refCnt), fBeginningOfData(0)
{ }
static sk_sp<Rec> Make(const char text[], size_t len);
uint32_t fLength; // logically size_t, but we want it to stay 32bits
mutable std::atomic<int32_t> fRefCnt;
char fBeginningOfData;
char* data() { return &fBeginningOfData; }
const char* data() const { return &fBeginningOfData; }
void ref() const;
void unref() const;
bool unique() const;
// Ensure the unsized delete is called.
void operator delete(void* p) { ::operator delete(p); }
sk_sp<Rec> fRec;
#ifdef SK_DEBUG
const SkString& validate() const;
const SkString& validate() const { return *this; }
static const Rec gEmptyRec;
/// Creates a new string and writes into it using a printf()-style format.
SkString SkStringPrintf(const char* format, ...);
/// This makes it easier to write a caller as a VAR_ARGS function where the format string is
/// optional.
static inline SkString SkStringPrintf() { return SkString(); }
static inline void swap(SkString& a, SkString& b) {
enum SkStrSplitMode {
// Strictly return all results. If the input is ",," and the separator is ',' this will return
// an array of three empty strings.
// Only nonempty results will be added to the results. Multiple separators will be
// coalesced. Separators at the beginning and end of the input will be ignored. If the input is
// ",," and the separator is ',', this will return an empty vector.
// Split str on any characters in delimiters into out. (Think, strtok with a sane API.)
void SkStrSplit(const char* str, const char* delimiters, SkStrSplitMode splitMode,
SkTArray<SkString>* out);
inline void SkStrSplit(const char* str, const char* delimiters, SkTArray<SkString>* out) {
SkStrSplit(str, delimiters, kCoalesce_SkStrSplitMode, out);