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Add a leniency flag to String.unescape(), and fix a memory leak in String.(un)escape() (#2640)

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* fix memory leak in string_escape.c3
* add unescape_lenient and tunescape_lenient
* Optimize for the use of the temp allocator.

---------

Co-authored-by: Christoffer Lerno <christoffer@aegik.com>
This commit is contained in:
Lexi
2025-12-12 18:49:01 -05:00
committed by GitHub
parent 0c0d0ace4d
commit 2a2c0f5d91
1 changed files with 172 additions and 144 deletions
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316
lib/std/core/string_escape.c3
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@@ -1,4 +1,4 @@
// Copyright (c) 2024 Christoffer Lerno. All rights reserved.
// Copyright (c) 2024-2025 Christoffer Lerno. All rights reserved.
// Use of this source code is governed by the MIT license
// a copy of which can be found in the LICENSE_STDLIB file.
@@ -22,43 +22,57 @@ faultdef INVALID_ESCAPE_SEQUENCE, UNTERMINATED_STRING, INVALID_HEX_ESCAPE, INVAL
*>
fn String String.escape(String s, Allocator allocator, bool strip_quotes = true)
{
// Conservative allocation: most strings need minimal escaping
usz initial_capacity = s.len + s.len / 5 + 2; // ~1.2x + quotes
DString result = dstring::new_with_capacity(allocator, initial_capacity);
// Conservative allocation: most strings need minimal escaping
usz initial_capacity = s.len + s.len / 5 + 2; // ~1.2x + quotes
if (!strip_quotes) result.append_char('"');
foreach (char c : s)
{
switch (c)
{
case '"': result.append(`\"`);
case '\\': result.append(`\\`);
case '\b': result.append(`\b`);
case '\f': result.append(`\f`);
case '\n': result.append(`\n`);
case '\r': result.append(`\r`);
case '\t': result.append(`\t`);
case '\v': result.append(`\v`);
case '\0': result.append(`\0`);
default:
if (c >= 32 && c <= 126)
{
// Printable ASCII
result.append_char(c);
}
else
{
// Non-printable, use hex escape
result.appendf("\\x%02x", (uint)c);
}
}
}
if (!strip_quotes) result.append_char('"');
return result.copy_str(allocator);
if (allocator == tmem)
{
DString result = dstring::new_with_capacity(tmem, initial_capacity);
escape_dstring(s, result, strip_quotes);
return result.str_view();
}
@pool()
{
DString result = dstring::temp_with_capacity(initial_capacity);
escape_dstring(s, result, strip_quotes);
return result.copy_str(allocator);
};
}
fn void escape_dstring(String s, DString result, bool strip_quotes) @private
{
if (!strip_quotes) result.append_char('"');
foreach (char c : s)
{
switch (c)
{
case '"': result.append(`\"`);
case '\\': result.append(`\\`);
case '\b': result.append(`\b`);
case '\f': result.append(`\f`);
case '\n': result.append(`\n`);
case '\r': result.append(`\r`);
case '\t': result.append(`\t`);
case '\v': result.append(`\v`);
case '\0': result.append(`\0`);
default:
if (c >= 32 && c <= 126)
{
// Printable ASCII
result.append_char(c);
}
else
{
// Non-printable, use hex escape
result.appendf("\\x%02x", (uint)c);
}
}
}
if (!strip_quotes) result.append_char('"');
}
<*
Escape a string using the temp allocator.
@@ -76,33 +90,33 @@ fn String String.tescape(String s, bool strip_quotes = false) => s.escape(tmem,
*>
fn usz escape_len(String s)
{
usz len = 2; // For quotes
foreach (char c : s)
{
switch (c)
{
case '"':
case '\\':
case '\b':
case '\f':
case '\n':
case '\r':
case '\t':
case '\v':
case '\0':
len += 2; // \X
default:
if (c >= 32 && c <= 126)
{
len += 1;
}
else
{
len += 4; // \xHH
}
}
}
return len;
usz len = 2; // For quotes
foreach (char c : s)
{
switch (c)
{
case '"':
case '\\':
case '\b':
case '\f':
case '\n':
case '\r':
case '\t':
case '\v':
case '\0':
len += 2; // \X
default:
if (c >= 32 && c <= 126)
{
len += 1;
}
else
{
len += 4; // \xHH
}
}
}
return len;
}
<*
@@ -111,10 +125,11 @@ fn usz escape_len(String s)
@param allocator : "The allocator to use for the result"
@param s : "The quoted string to unescape"
@param allow_unquoted : "Set to true to unescape strings not surrounded by quotes, defaults to false"
@param lenient : "Be lenient with escapes, resolving unknown sequences to the escape character, defaults to false"
@return "The unescaped string without quotes, safe to convert to ZString"
@return? UNTERMINATED_STRING, INVALID_ESCAPE_SEQUENCE, INVALID_HEX_ESCAPE, INVALID_UNICODE_ESCAPE
*>
fn String? String.unescape(String s, Allocator allocator, bool allow_unquoted = false)
fn String? String.unescape(String s, Allocator allocator, bool allow_unquoted = false, bool lenient = false)
{
if (s.len >= 2 && s[0] == '"' && s[^1] == '"')
{
@@ -123,78 +138,90 @@ fn String? String.unescape(String s, Allocator allocator, bool allow_unquoted =
}
else if (!allow_unquoted) return UNTERMINATED_STRING?;
// Handle empty string case
if (!s.len)
{
return "".copy(allocator);
}
DString result = dstring::new_with_capacity(allocator, s.len);
// Handle empty string case
if (!s.len)
{
return "".copy(allocator);
}
if (allocator == tmem)
{
DString result = dstring::new_with_capacity(tmem, s.len);
unescape_dstring(s, result, allow_unquoted, lenient)!;
return result.str_view();
}
@pool()
{
DString result = dstring::temp_with_capacity(s.len);
unescape_dstring(s, result, allow_unquoted, lenient)!;
return result.copy_str(allocator);
};
}
fn void? unescape_dstring(String s, DString result, bool allow_unquoted = false, bool lenient = false) @private
{
usz len = s.len;
for (usz i = 0; i < len; i++)
{
char c = s[i];
if (c != '\\')
{
result.append_char(c);
continue;
}
if (c != '\\')
{
result.append_char(c);
continue;
}
// Handle escape sequence
if (i + 1 >= len) return INVALID_ESCAPE_SEQUENCE?;
// Handle escape sequence
if (i + 1 >= len) return INVALID_ESCAPE_SEQUENCE?;
char escape_char = s[++i];
switch (escape_char)
{
case '"': result.append_char('"');
case '\\': result.append_char('\\');
case '/': result.append_char('/');
case 'b': result.append_char('\b');
case 'f': result.append_char('\f');
case 'n': result.append_char('\n');
case 'r': result.append_char('\r');
case 't': result.append_char('\t');
case 'v': result.append_char('\v');
case '0': result.append_char('\0');
case 'x':
// Hex escape \xHH
if (i + 2 >= len) return INVALID_HEX_ESCAPE?;
char h1 = s[++i];
char h2 = s[++i];
if (!h1.is_xdigit() || !h2.is_xdigit()) return INVALID_HEX_ESCAPE?;
uint val = h1 > '9' ? (h1 | 32) - 'a' + 10 : h1 - '0';
val = val << 4;
val += h2 > '9' ? (h2 | 32) - 'a' + 10 : h2 - '0';
result.append_char((char)val);
case 'u':
// Unicode escape \uHHHH
if (i + 4 >= len) return INVALID_UNICODE_ESCAPE?;
uint val;
for (int j = 0; j < 4; j++)
{
char hex_char = s[++i];
if (!hex_char.is_xdigit()) return INVALID_UNICODE_ESCAPE?;
val = val << 4 + (hex_char > '9' ? (hex_char | 32) - 'a' + 10 : hex_char - '0');
}
result.append_char32(val);
case 'U':
// Unicode escape \UHHHHHHHH
if (i + 8 >= len) return INVALID_UNICODE_ESCAPE?;
uint val;
for (int j = 0; j < 8; j++)
{
char hex_char = s[++i];
if (!hex_char.is_xdigit()) return INVALID_UNICODE_ESCAPE?;
val = val << 4 + (hex_char > '9' ? (hex_char | 32) - 'a' + 10 : hex_char - '0');
}
result.append_char32(val);
default:
return INVALID_ESCAPE_SEQUENCE?;
}
}
return result.copy_str(allocator);
char escape_char = s[++i];
switch (escape_char)
{
case '"': result.append_char('"');
case '\\': result.append_char('\\');
case '/': result.append_char('/');
case 'b': result.append_char('\b');
case 'f': result.append_char('\f');
case 'n': result.append_char('\n');
case 'r': result.append_char('\r');
case 't': result.append_char('\t');
case 'v': result.append_char('\v');
case '0': result.append_char('\0');
case 'x':
// Hex escape \xHH
if (i + 2 >= len) return INVALID_HEX_ESCAPE?;
char h1 = s[++i];
char h2 = s[++i];
if (!h1.is_xdigit() || !h2.is_xdigit()) return INVALID_HEX_ESCAPE?;
uint val = h1 > '9' ? (h1 | 32) - 'a' + 10 : h1 - '0';
val = val << 4;
val += h2 > '9' ? (h2 | 32) - 'a' + 10 : h2 - '0';
result.append_char((char)val);
case 'u':
// Unicode escape \uHHHH
if (i + 4 >= len) return INVALID_UNICODE_ESCAPE?;
uint val;
for (int j = 0; j < 4; j++)
{
char hex_char = s[++i];
if (!hex_char.is_xdigit()) return INVALID_UNICODE_ESCAPE?;
val = val << 4 + (hex_char > '9' ? (hex_char | 32) - 'a' + 10 : hex_char - '0');
}
result.append_char32(val);
case 'U':
// Unicode escape \UHHHHHHHH
if (i + 8 >= len) return INVALID_UNICODE_ESCAPE?;
uint val;
for (int j = 0; j < 8; j++)
{
char hex_char = s[++i];
if (!hex_char.is_xdigit()) return INVALID_UNICODE_ESCAPE?;
val = val << 4 + (hex_char > '9' ? (hex_char | 32) - 'a' + 10 : hex_char - '0');
}
result.append_char32(val);
default:
if (!lenient) return INVALID_ESCAPE_SEQUENCE?;
result.append_char(escape_char);
}
}
}
<*
@@ -202,10 +229,11 @@ fn String? String.unescape(String s, Allocator allocator, bool allow_unquoted =
@param s : "The quoted string to unescape"
@param allow_unquoted : "Set to true to unescape strings not surrounded by quotes, defaults to false"
@param lenient : "Be lenient with escapes, resolving unknown sequences to the escape character, defaults to false"
@return "The unescaped string without quotes"
@return? UNTERMINATED_STRING, INVALID_ESCAPE_SEQUENCE, INVALID_HEX_ESCAPE, INVALID_UNICODE_ESCAPE
*>
fn String? String.tunescape(String s, bool allow_unquoted = false) => s.unescape(tmem, allow_unquoted);
fn String? String.tunescape(String s, bool allow_unquoted = false, bool lenient = false) => s.unescape(tmem, allow_unquoted, lenient);
<*
Check if a character needs to be escaped in a string literal.
@@ -215,19 +243,19 @@ fn String? String.tunescape(String s, bool allow_unquoted = false) => s.unescape
*>
fn bool needs_escape(char c)
{
switch (c)
{
case '"':
case '\\':
case '\b':
case '\f':
case '\n':
case '\r':
case '\t':
case '\v':
case '\0':
return true;
default:
return c < 32 || c > 126;
}
switch (c)
{
case '"':
case '\\':
case '\b':
case '\f':
case '\n':
case '\r':
case '\t':
case '\v':
case '\0':
return true;
default:
return c < 32 || c > 126;
}
}