Perl 6 parser/compiler ^

This is a Perl 6 parser/compiler, an early version (no version numbers yet). It's still very early, only simple expressions and functions are available. If you're in a hurry to write "real Perl 6" programs, you might try looking at Pugs -- http://www.pugscode.org. Or, you can send patches and contributions to the one being built here!

However, even though this is not a complete compiler yet, you can still see how Perl 6 programs are parsed, help us create test cases, and extend/improve the grammar and runtime to cover more of Perl 6. Here's how the system currently works:

Compiling ^

The perl6 parser/compiler lives in the perl6.pbc file. To create this file, simply issue the command

  $ make

To invoke perl6 from a shell prompt on a (Perl 6) input file named "foo.p6", use:

  $ parrot perl6.pbc foo.p6

To run interactively, entering single-line statements:

  $ parrot perl6.pbc

To display the parse tree, add the "--target=parse" option:

  $ parrot perl6.pbc --target=parse foo.p6

Or, to display the abstract syntax tree, the opcode syntax tree, or the generated PIR code, use "--target=PAST", "--target=POST", or "--target=PIR".

To get a dump of the parser's operator precedence table, use --dump-optable:

  $ parrot perl6.pbc --dump-optable

Files ^

The "top" file for the parser is perl6.pir which is used to create the perl6.pbc file. It initializes the overall parsing system and registers the parser as a Parrot "Perl6" compiler.

The other files needed for the compiler are in the src/ subdirectory.

The src/grammar_rules.pg file defines the "top-down" grammar used for large Perl 6 program structures, defined using rules in Perl 6 rules syntax. The src/grammar_optok.pg file defines the operator tokens used for expression parsing with PGE's operator-precedence parser. The tokens in src/grammar_optok.pge are defined using a pseudo-Perl6 syntax. PGE's "pgc.pir" compiler is then used to compile the two grammar files into src/grammar_gen.pir, which is included by perl6.pir. (See Synopsis 5 for more details on Perl 6 rules syntax, and compilers/pge/ for more details about PGE.)

The src/parse.pir file defines a few special-purpose rules needed to support parsing that are better written directly in PIR instead of using the rules or token syntax. Currently this file defines the <expression> rule, which just calls into the operator precedence parser.

The file src/pge2past.tg is a tree grammar that specifies how to convert the parse tree into the abstract syntax tree (PAST), and src/past2post.tg generates POST from PAST.

The src/main.pir file controls what happens when the perl6.pbc file is invoked directly from parrot (as opposed to being loaded via the load_bytecode op).

The PIR files in src/ are included as part of compiling perl6.pir to produce perl6.pbc.

The perl6.pbc file can also be used to compile Perl 6 code from PIR:

    load_bytecode "perl6.pbc"
    $S0 = 'say "hello world"'            # source code to compile
    $P0 = compreg("Perl6")               # obtain the compiler
    $P1 = $P0($S0)                       # compile source code
    $P1()                                # execute

One can also provide the "target" option to the compiler:

    $P1 = $P0($S0, 'target'=>'parse')    # obtain parse tree
    $P1 = $P0($S0, 'target'=>'PAST')     # get AST
    $P1 = $P0($S0, 'target'=>'POST')     # get OST
    $P1 = $P0($S0, 'target'=>'PIR')      # get PIR

Testing ^

To run the parrot-specific tests:

 make test

To run the official test suite:

 make spectest

Note that this requires svn: it exports a copy of the official tests to a a local directory (once) and runs those tests. Right now we only run tests we're sure we might pass.

AUTHOR ^

Patrick Michaud (pmichaud@pobox.com) is the author and maintainer. Patches and suggestions should be sent to the Perl 6 compiler list (perl6-compiler@perl.org).


 parrot