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// Copyright 1999-2005 The RE2 Authors. All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "util/util.h"
#include "re2/stringpiece.h"
namespace re2 {
// ----------------------------------------------------------------------
// CEscapeString()
// Copies 'src' to 'dest', escaping dangerous characters using
// C-style escape sequences. 'src' and 'dest' should not overlap.
// Returns the number of bytes written to 'dest' (not including the \0)
// or -1 if there was insufficient space.
// ----------------------------------------------------------------------
int CEscapeString(const char* src, int src_len, char* dest,
int dest_len) {
const char* src_end = src + src_len;
int used = 0;
for (; src < src_end; src++) {
if (dest_len - used < 2) // Need space for two letter escape
return -1;
unsigned char c = *src;
switch (c) {
case '\n': dest[used++] = '\\'; dest[used++] = 'n'; break;
case '\r': dest[used++] = '\\'; dest[used++] = 'r'; break;
case '\t': dest[used++] = '\\'; dest[used++] = 't'; break;
case '\"': dest[used++] = '\\'; dest[used++] = '\"'; break;
case '\'': dest[used++] = '\\'; dest[used++] = '\''; break;
case '\\': dest[used++] = '\\'; dest[used++] = '\\'; break;
default:
// Note that if we emit \xNN and the src character after that is a hex
// digit then that digit must be escaped too to prevent it being
// interpreted as part of the character code by C.
if (c < ' ' || c > '~') {
if (dest_len - used < 4) // need space for 4 letter escape
return -1;
sprintf(dest + used, "\\%03o", c);
used += 4;
} else {
dest[used++] = c; break;
}
}
}
if (dest_len - used < 1) // make sure that there is room for \0
return -1;
dest[used] = '\0'; // doesn't count towards return value though
return used;
}
// ----------------------------------------------------------------------
// CEscape()
// Copies 'src' to result, escaping dangerous characters using
// C-style escape sequences. 'src' and 'dest' should not overlap.
// ----------------------------------------------------------------------
string CEscape(const StringPiece& src) {
const int dest_length = src.size() * 4 + 1; // Maximum possible expansion
char* dest = new char[dest_length];
const int len = CEscapeString(src.data(), src.size(),
dest, dest_length);
string s = string(dest, len);
delete[] dest;
return s;
}
string PrefixSuccessor(const StringPiece& prefix) {
// We can increment the last character in the string and be done
// unless that character is 255, in which case we have to erase the
// last character and increment the previous character, unless that
// is 255, etc. If the string is empty or consists entirely of
// 255's, we just return the empty string.
bool done = false;
string limit(prefix.data(), prefix.size());
int index = limit.length() - 1;
while (!done && index >= 0) {
if ((limit[index]&255) == 255) {
limit.erase(index);
index--;
} else {
limit[index]++;
done = true;
}
}
if (!done) {
return "";
} else {
return limit;
}
}
} // namespace re2
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