Features / bug fixes in the preprocessor:
- Add word boundary after regex for preprocessor token matching.
Previously, when you mistakenly used "#ifdef" instead of "#if", the
line would be parsed as a preprocessor directive (because "#ifdef"
starts with "#if"), but without condition (because "def" does not
start with a space). Consequently, the condition would always be false
and anything between "#ifdef" and "#endif" would not be included.
- Add validation and error reporting everywhere, to aid debugging.
- Support nested comments (by accounting for the whole stack of
conditions, instead of only the current one).
- Add #elif preprocessor command. Could be used as follows:
//#if !FEATURE_ENABLED
//#error FEATURE_ENABLED must be set
//#endif
- Add #error preprocessor command.
- Add end-of-line word boundary after "-->" in the comment trimmer.
Otherwise the pattern would also match "-->" in the middle of a line,
and incorrectly convert something like "while(i-->0)" to "while(i0)".
Code health:
- Add unit tests for the preprocessor (run external/builder/test.js).
- Fix broken link to MDN (resolved to DXR).
- Refactor to use STATE_* names instead of magic numbers (the original
meaning of the numbers is preserved, with one exception).
- State 3 has been split in two states, to distinguish between being in
an #if and #else. This is needed to ensure that #else cannot be
started without an #if.
