Getting rid of the |trackLineAndColumn| simplifies the code generator
(by unifying two paths in the code).
The |line| and |column| functions currently always compute all the
position info from scratch, which is horribly ineffective. This will be
improved in later commit(s).
This will allow to compute position data lazily and get rid of the
|trackLineAndColumn| option without affecting performance of generated
parsers that don't use position data.
Before this commit, |PEG.buildParser| always returned a parser object.
The only way to get its source code was to call the |toSource| method on
it. While this method worked for parsers produced by |PEG.buildParser|
directly, it didn't work for parsers instantiated by executing their
source code. In other words, it was unreliable.
This commit remvoes the |toSource| method on generated parsers and
introduces a new |output| option to |PEG.buildParser|. It allows callers
to specify whether they want to get back the parser object
(|options.output === "parser"|) or its source code (|options.output ===
"source"|). This is much better and more reliable API.
Includes:
* Moving the source code from /src to /lib.
* Adding an explicit file list to package.json
* Updating the Makefile.
* Updating the spec and benchmark suites and their READMEs.
Part of a fix for GH-32.
Before this commit, generated parser were able to start parsing from any
rule. This was nice, but it made rule code inlining impossible.
Since this commit, the list of allowed start rules has to be specified
explicitly using the |allowedStartRules| option of the |PEG.buildParser|
method (or the --allowed-start-rule option on the command-line). These
rules will be excluded from inlining when it's implemented.
This commit replaces the |startRule| parameter of the |parse| method in
generated parsers with more generic |options| -- an options object. This
options object can be used to pass custom options to the parser because
it is visible as the |options| variable inside parser code.
The start rule can now be specified as the |startRule| option. This
means you have to replace all calls like:
parser.parse("input", "myStartRule");
with
parser.parse("input", { startRule: "myStartRule" });
Closes GH-37.
The purpose of this change is to avoid the need to index register
variables storing match results of sequences whose elements are labeled.
The indexing happened when match results of labeled elements were passed
to action/predicate functions.
In order to avoid indexing, the register allocator needs to ensure that
registers storing match results of any labeled sequence elements are
still "alive" after finishing parsing of the sequence. They should not
be used to store anything else at least until code of all actions and
predicates that can see the labels is executed. This requires that the
|allocateRegisters| pass has the knowledge of scoping. Because that
knowledge was already implicitly embedded in the |coputeParams| pass,
the logical step to prevent duplication was to merge it with the
|allocateRegisters| pass. This is what this commit does.
As a part of the merge the tests of both passes were largely refactored.
This is both to accomodate the merge and to make the tests in sync with
the code again (the tests became a bit out-of-sync during the last few
commits -- they tested more than was needed).
The speed/size impact is slightly positive:
Speed impact
------------
Before: 849.86 kB/s
After: 858.16 kB/s
Difference: 0.97%
Size impact
-----------
Before: 876618 b
After: 875602 b
Difference: -0.12%
(Measured by /tools/impact with Node.js v0.6.18 on x86_64 GNU/Linux.)
This commit changes the model underlying parser variables used to store
match results and parse positions. Until now they were treated as a
stack, now they are thought of as registers. The actual behavior does
not change (yet), only the terminology.
More specifically, this commit:
* Changes parser variable names from |result0|, |result1|, etc. to
|r0|, |r1|, etc.
* Changes various internal names and comments to match the new model.
* Renames the |computeVarIndices| pass to |allocateRegisters|.
One stack is conceptually simpler, requires less code and will make a
transition to a register-based machine easier.
Note that the stack variables are now named a bit incorrectly
(|result0|, |result1|, etc. even when they store also parse positions).
I didn't bother with renaming because a transition to a register-based
machine will follow soon and the names will change anyway.
The speed/size impact is insignificant.
Speed impact
------------
Before: 839.05 kB/s
After: 839.67 kB/s
Difference: 0.07%
Size impact
-----------
Before: 949783 b
After: 961578 b
Difference: 1.24%
(Measured by /tools/impact with Node.js v0.6.18 on x86_64 GNU/Linux.)
This commit replaces all variable name computations in |computeVarNames|
and |computeParams| passes by computations of indices. The actual names
are computed later in the |generateCode| pass.
This change makes the code generator the only place that deals with the
actual variable names, making them easier to change for example.
The code generator code seems bit more complicated after the change, but
this complexity will pay off (and mostly disappear) later.
Places all code that does something with "action" AST nodes under code
handling "choice" nodes.
This ordering is logical because now all the node handling code matches
the sequence in which various node types usually appear when descending
through the AST tree.
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