This is mostly done for consistency with the JavaScript example grammar,
from which the |Identifier| rule is taken from. See the previous commit
for details.
Instead of matching segments between blocks character by character,
match them as a whole. Also align the style with other similar rules
(e.g. the comment ones).
Before this commit, line continuations in character classes contributed
an empty string to the list of characters and character ranges matched
by a class. While this didn't lead to a buggy behavior with the current
code generator, the AST was wrong and the problem could have caused bugs
later.
This commit fixes the problem.
Semantic predicates are kind of |PrimaryExpression|, not kind of
|PrefixedExpression|. Therefore I extracted a rule for them and
referenced it from the |PrimaryExpression|.
Initializer and rules are now separated in a similar way as JavaScript
statements -- either by a semicolon or a line terminator, possibly with
whitespace and comments mixed in.
One consequence is that the grammars like this are now illegal:
foo = "a" bar = "b"
A semicolon needs to be inserted between the rules:
foo = "a";bar = "b"
I consider this a good change as the now-illegal syntax was somewhat
confusing.
This makes the |Primary| rule a bit more tidy. Also, matching the |.|
character really belongs to the lexical part of the grammar, next to
literals and character classes.
* Rename the |Action| rule to |CodeBlock| (it better describes what
the rule matches).
* Implement the rule in a simpler way and move it after more basic
lexical elements.
This change has two side effects:
* Label names can no longer be JavaScript reserved words.
* |$| is allowed again in label names. However, because of the
preference rules, names starting with it will be usually parsed as a
text operator followed by another identifier (denoting a rule
reference or label name).
Before this commit, whitespace was handled at the lexical level by
making tokens consume any whitespace coming after them. This was
accomplished by appending |__| to every token rule.
This commit changes whitespace handling to be more explicit. Tokens no
longer consume whitespace coming after them and syntactic rules have to
cope with it. While this slightly complicates the syntactic grammar, I
think it's a cleaner way. Moreover, it is what JavaScript example
grammar does.
One small side-effect of thich change is that the grammar is now
stand-alone (it doesn't require utils.js anymore).
When rule names are capitalized, it's easier to visually distinguish
them from non-capitalized label names. Moreover, I use capitalized rule
names in all my grammars these days.
Before this commit, a line continuation (backslash followed by a line
terminator character) contributed a character to a string or a character
class it was used in. In JavaScript and many other languages, line
continuation doesn't contribute anything.
This commit aligns PEG.js line continuation behavior with JavaScript.
Before this commit, the value of the |rawText| property of "class" AST
nodes was created in a hackish way from processed input and it didn't
always exactly represent the actual input text.
This commit changes the code so that the value of the |rawText| property
is created using the |text| function. This is a clean way which also
resolves the exact representation problem.
Also added few missing |hasOwnProperty| calls that JSHint didn't detect
because it only looks whether there is an |if| statement wrapping the
loop body.
Fixes the following JSHint errors (which I think are JSHint bugs):
spec/parser.spec.js: line 142, col 20, Bad for in variable 'key'.
spec/generated-parser.spec.js: line 119, col 20, Bad for in variable 'key'.
Implement a new syntax to extract matched strings from expressions. For
example, instead of:
identifier = first:[a-zA-Z_] rest:[a-zA-Z0-9_]* { return first + rest.join(""); }
you can now just write:
identifier = $([a-zA-Z_] [a-zA-Z0-9_]*)
This is useful mostly for "lexical" rules at the bottom of many
grammars.
Note that structured match results are still built for the expressions
prefixed by "$", they are just ignored. I plan to optimize this later
(sometime after the code generator rewrite).
Changes all code that does something with "literal", "class" or "any"
AST nodes so that the code deals with these in the follwing order:
1. literal
2. class
3. any
Previously the code used this ordering:
1. literal
2. any
3. class
The new ordering is more logical because the nodes are handled from the
most specific to the most generic.
PEG.js grammar rules are represented by |rule| nodes in the AST. Until
now, all such nodes had a |displayName| property which was either |null|
or stored rule's human-readable name. This commit gets rid of the
|displayName| property and starts representing rules with a
human-readable name using a new |named| node (a child of the |rule|
node).
This change simplifies code generation code a bit as tests for
|displayName| can be removed (see changes in generate-code.js). It also
separates different concerns from each other nicely.
This change makes code using |oneRuleGrammar| less verbose + prepares
for passing of the initializer (will be used by code added in the next
few commits).
David Majda
David Majda