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447212fa65
This avoids C++'s standard library regexes, which aren't the same
across platforms, and have many other issues, like using stack
so much that they stack overflow when processing a lot of data.
To avoid backwards and forward compatibility issues, regexes are
processed using a function converting libstdc++ regexes into Boost
regexes, escaping characters that Boost needs to have escaped, and
rejecting features that Boost has and libstdc++ doesn't.
Related context:
- Original failed attempt to use `boost::regex` in CppNix, failed due to
boost icu dependency being large (disabling ICU is no longer necessary
because linking ICU requires using a different header file,
`boost/regex/icu.hpp`): https://github.com/NixOS/nix/pull/3826
- An attempt to use PCRE, rejected due to providing less backwards
compatibility with `std::regex` than `boost::regex`:
https://github.com/NixOS/nix/pull/7336
- Second attempt to use `boost::regex`, failed due to `}` regex failing
to compile (dealt with by writing a wrapper that parses a regular
expression and escapes `}` characters):
https://github.com/NixOS/nix/pull/7762
Closes #34. Closes #476.
Change-Id: Ieb0eb9e270a93e4c7eed412ba4f9f96cb00a5fa4
1,004 B
1,004 B
| synopsis | issues | cls | category | credits | ||||
|---|---|---|---|---|---|---|---|---|
| Replace regex engine with boost::regex |
|
|
Fixes |
|
Previously, the C++ standard regex expression library was used, the behaviour of which varied depending on the platform. This has been replaced with the Boost regex library, which works identically across platforms.
The visible behaviour of the regex functions doesn't change. While the new library has more features, Lix will reject regular expressions using them.
This also fixes regex matching reporting stack overflow when matching on too much data.
Before:
nix-repl> builtins.match ".*" (
builtins.concatStringsSep "" (
builtins.genList (_: "a") 1000000
)
)
error: stack overflow (possible infinite recursion)
After:
nix-repl> builtins.match ".*" (
builtins.concatStringsSep "" (
builtins.genList (_: "a") 1000000
)
)
[ ]