You cannot select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
David Majda 57e806383c Error handling: Use a special value (not |null|) to indicate failure
Using a special value to indicate match failure instead of |null| allows
actions to return |null| as a regular value. This simplifies e.g. the
JSON parser.

Note the special value is internal and intentionally undocumented. This
means that there is currently no official way how to trigger a match
failure from an action. This is a temporary state which will be fixed
soon.

The negative performance impact (see below) is probably caused by
changing lot of comparisons against |null| (which likely check the value
against a fixed constant representing |null| in the interpreter) to
comparisons against the special value (which likely check the value
against another value in the interpreter).

Implements part of #198.

Speed impact
------------
Before:     1146.82 kB/s
After:      1031.25 kB/s
Difference: -10.08%

Size impact
-----------
Before:     950817 b
After:      973269 b
Difference: 2.36%

(Measured by /tools/impact with Node.js v0.6.18 on x86_64 GNU/Linux.)
11 years ago
..
compiler Error handling: Use a special value (not |null|) to indicate failure 11 years ago
compiler.js Plugin API: Split compiler passes into stages 12 years ago
grammar-error.js Git repo npmization: Make the repo a npm package 12 years ago
parser.js Error handling: Use a special value (not |null|) to indicate failure 11 years ago
peg.js Plugin API: Split compiler passes into stages 12 years ago
utils.js Fix typo in comment 11 years ago