40 Commits (b271d6644216228af6260151328aebdb269b7942)

Author SHA1 Message Date
David Majda b271d66442 JavaScript example: Fix automatic semicolon insertion
Fix parsing of inputs like this:

  foo() // comment
  bar()
10 years ago
David Majda c70c8551b4 JavaScript example: Fix parsing of statements
Fixes a problem where statements starting with a reserved word produced
errors like this:

  Reserved word "return" can't be used as an identifier.

The problem was in a wrong ordering of choices in the |Statement| rule
together with aggressive reserved word detection in the |Identifier|
rule.
10 years ago
David Majda 2005345976 Complete rewrite of the CSS example grammar
This is a complete rewrite of the CSS example grammar. It is now based
on CSS 2.1 *including the errata* and the generated parser builds a
nicer syntax tree. There is also a number of cleanups, formatting
changes, naming changes, and bug fixes.

Beside this, the rewrite reflects how I write grammars today (as opposed
to few years ago) and what style I would recommend to others.
10 years ago
David Majda 18f92c5647 Complete rewrite of the JavaScript example grammar
This is a complete rewrite of the JavaScript example grammar. It is now
based on ECMA-262, 5.1 Edition and the generated parser builds a syntax
tree compatible with Mozilla SpiderMonkey Parser API. There is also a
number of cleanups, formatting changes, naming changes, and bug fixes.

Beside this, the rewrite reflects how I write grammars today (as opposed
to few years ago) and what style I would recommend to others.
10 years ago
David Majda fba70833dd Complete rewrite of the JSON example grammar
This is a complete rewrite of the JSON example grammar. It is now based
on RFC 7159 instead of an informal description at the JSON website.

Beside this, the rewrite reflects how I write grammars today (as opposed
to few years ago) and what style I would recommend to others.
10 years ago
David Majda f5443d2bf1 Complete rewrite of the arithmetics example grammar
This is a complete rewrite of the arithmetics example grammar. It now
allows whitespace between tokens, supports "-" and "/" operators, and
gets the operator associativity right. Also, rule names now match the usual
conventions (term, factor,...).

Beside this, the rewrite reflects how I write grammars today (as opposed
to few years ago) and what style I would recommend to others.
11 years ago
David Majda da9a32a5f3 Example grammars: Improve |parseInt| invocations
Instead of |parseInt("0x" + digits)| do |parseInt(digits, 16)|, which is
a bit cleaner.
11 years ago
David Majda 68c6452d8a CSS example grammar: Simplify |integer| and |float| rules
It's not necessary to parse |parts| in the |integer| and |float| rule
into integer/float value. Everywhere these rules are used the result is
converted back into string anyway.
11 years ago
David Majda 86769a6c5c Error handling: Make |?| return |null| on unsuccessful match
Before this commit, the |?| operator returned an empty string upon
unsuccessful match. This commit changes the returned value to |null|. It
also updates the PEG.js grammar and the example grammars, which used the
value returned by |?| quite often.

Returning |null| is possible because it no longer indicates a match
failure.

I expect that this change will simplify many real-world grammars, as an
empty string is almost never desirable as a return value (except some
lexer-level rules) and it is often translated into |null| or some other
value in action code.

Implements part of #198.
11 years ago
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
David Majda f3d392bd1c JavaScript example: Fix handling of elided elements in array literals
JavaScript allows one to skip (elide) elements in array literals. It
also allows a trailing comma, which doesn't imply an element elision.

For example, an array literal:

  [,,,]

contains three elided elements (one before each comma) and a trailing
comma.

Example JavaScript parser handled elided elements incorrectly and just
threw them away. This commit fixes this behvior and inserts |null| in
the AST for each elided element. This is in line with how SpiderMonkey's
JavaScript parser (the |Reflect.parse| API), Esprima and Acorn behave.

Based on a patch by @fpirsch:

  https://github.com/dmajda/pegjs/pull/177
11 years ago
David Majda d71bca46a1 Javascript example: Improve array literal rules
Makes the |ArrayLiteral| and |ElementList| rules more in line with the
ECMAScript grammar.

Based on a patch by @fpirsch:

  https://github.com/dmajda/pegjs/pull/177
11 years ago
David Majda fe18c6ffd3 Fix |null| handling in the JSON parser
We couldn't return |null| in the |value| rule of the JSON example
parser because that would mean parse failure. So until now, we just
returned |"null"| (a string).

This was obviously stupid, so this commit changes the |value| rule to
return a special object instead that is converted to |null| later.

Based on patches by Patrick Logan (GH-91) and Jakub Vrána (GH-191).
11 years ago
fpirsch d7e853b87c Fix automatic semi-colon insertion
Fix automatic semi-colon insertion in var statements without
initialisers.
var i
i = 1;
is valid and not accepted by the parser

but
var i = 2
i = 3;
is valid and accepted by the parser, as it should be.

With this fix, both are accepted.
12 years ago
David Majda c54483bb17 Text nodes: Use text nodes in examples/javascript.pegjs 12 years ago
David Majda faaf9b6be1 Text nodes: Use text nodes in examples/css.pegjs 12 years ago
David Majda d0dfe46550 Text nodes: Use text nodes in examples/json.pegjs 12 years ago
David Majda 9ec6b6aa57 Text nodes: Use text nodes in examples/arithmetics.pegjs 12 years ago
fpirsch fa05142292 Update examples/javascript.pegjs
Changed "arguments" to "args" in several places to avoid shadowing "arguments", which is not allowed by Google Clusure Compiler.
12 years ago
David Majda 70e4166bb2 Fix typo in a comment in JavaScript example grammar 13 years ago
David Majda 8ae3eea7c4 Fix typo in JavaScript example grammar
Fixes GH-62.
13 years ago
Jason Davies d386d3a351 Fix typo in comment. 13 years ago
David Majda 5cf66d824c Fix typo in JavaScript example grammar 13 years ago
David Majda 5f810f803b Make example grammars compatible with Rhino 14 years ago
David Majda ee8c121676 Use labeled expressions and variables instead of $1, $2, etc.
Labeled expressions lead to more maintainable code and also will allow
certain optimizations (we can ignore results of expressions not passed
to the actions).

This does not speed up the benchmark suite execution statistically
significantly on V8.

Detailed results (benchmark suite totals):

---------------------------------
 Test #     Before       After
---------------------------------
      1   28.43 kB/s   28.46 kB/s
      2   28.38 kB/s   28.56 kB/s
      3   28.22 kB/s   28.58 kB/s
      4   28.76 kB/s   28.55 kB/s
      5   28.57 kB/s   28.48 kB/s
---------------------------------
Average   28.47 kB/s   28.53 kB/s
---------------------------------

Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/533.4 (KHTML, like Gecko) Chrome/5.0.375.55 Safari/533.4
14 years ago
David Majda 409ddf2ae8 Formatted all grammars more consistently and transparently
This is purely cosmetical change, no functionality was affected
(hopefully).
14 years ago
David Majda 698564a3c2 Replace ":" after a rule name with "="
I'll introduce labelled expressions shortly and I want to use ":" as a
label-expression separator. This change avoids conflict between the two
meanings of ":". (What would e.g. "foo: 'bar'" mean?  Rule "foo"
matching string "bar", or string "bar" labelled "foo"?)
14 years ago
David Majda f9ea46ef15 Fix string literal parsing in the JavaScript grammar 14 years ago
David Majda 11c67b0507 Remove trailing whitespace 14 years ago
David Majda de7536fd94 Added notes about ECMA-262, 5th ed. compatibility to the JSON example grammar. 14 years ago
David Majda 7fc491412d Work around the fact that IE does not recognize "\v" in strings. 14 years ago
David Majda 6a194e8f68 Added example JavaScript parser. 14 years ago
David Majda 751a33715d Added example CSS parser. 15 years ago
David Majda a1adbf0607 Added example JSON parser. 15 years ago
David Majda 8f2aa1e834 Fixed a bug in the example grammar where integers beginning with 0 were parsed as octal. 15 years ago
David Majda aff85fd228 Removed subtraction and division from the example grammar because of wrong associativity. 15 years ago
David Majda 9d239db2d6 Simplified the example arithmetics grammar once more + addded comment. 15 years ago
David Majda 1ee0049b08 Changed standard grammar extension from .peg to .pegjs (it is more specific). 15 years ago
David Majda eade133ea6 Simplified the example arithmetics grammar. 15 years ago
David Majda c3dd696a3e Initial commit. 15 years ago