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107 lines
4.7 KiB
Plaintext
107 lines
4.7 KiB
Plaintext
The PDE Preprocessor is based on the Java Grammar that comes with
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ANTLR 2.7.2. Moving it forward to a new version of the grammar
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shouldn't be too difficult.
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Here's some info about the various files in this directory:
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java.g: this is the ANTLR grammar for Java 1.3/1.4 from the ANTLR
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distribution. It is in the public domain. The only change to this
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file from the original this file is the uncommenting of the clauses
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required to support assert().
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java.tree.g: this describes the Abstract Syntax Tree (AST) generated
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by java.g. It is only here as a reference for coders hacking on the
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preprocessor, it is not built or used at all. Note that pde.g
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overrides some of the java.g rules so that in PDE ASTs, there are a
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few minor differences. Also in the public domain.
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pde.g: this is the grammar and lexer for the PDE language itself. It
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subclasses the java.g grammar and lexer. There are a couple of
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overrides to java.g that I hope to convince the ANTLR folks to fold
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back into their grammar, but most of this file is highly specific to
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PDE itself.
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PdeEmitter.java: this class traverses the AST generated by the PDE
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Recognizer, and emits it as Java code, doing any necessary
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transformations along the way. It is based on JavaEmitter.java,
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available from antlr.org, written by Andy Tripp <atripp@comcast.net>,
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who has given permission for it to be distributed under the GPL.
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ExtendedCommonASTWithHiddenTokens.java: this adds a necessary
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initialize() method, as well as a number of methods to allow for XML
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serialization of the parse tree in a such a way that the hidden tokens
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are visible. Much of the code is taken from the original
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CommonASTWithHiddenTokens class. I hope to convince the ANTLR folks
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to fold these changes back into that class so that this file will be
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unnecessary.
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TokenStreamCopyingHiddenTokenFilter.java: this class provides
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TokenStreamHiddenTokenFilters with the concept of tokens which can be
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copied so that they are seen by both the hidden token stream as well
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as the parser itself. This is useful when one wants to use an
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existing parser (like the Java parser included with ANTLR) that throws
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away some tokens to create a parse tree which can be used to spit out
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a copy of the code with only minor modifications. Partially derived
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from ANTLR code. I hope to convince the ANTLR folks to fold this
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functionality back into ANTLR proper as well.
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whitespace_test.pde: a torture test to ensure that the preprocessor is
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correctly preserving whitespace, comments, and other hidden tokens
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correctly. See the comments in the code for details about how to run
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the test.
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All other files in this directory are generated at build time by ANTLR
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itself. The ANTLR manual goes into a fair amount of detail about the
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what each type of file is for.
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....
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Current Preprocessor Subsitutions:
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"compiler.substitute_floats" (currently "substitute_f")
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- treat doubles as floats, i.e. 12.3 becomes 12.3f so that people
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don't have to add f after their numbers all the time. this is
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confusing for beginners.
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"compiler.enhanced_casting"
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- byte(), char(), int(), float() works for casting. this is basic in
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the current implementation, but should be expanded as described
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above. color() works similarly to int(), however there is also a
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*function* called color(r, g, b) in p5. will this cause trouble?
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"compiler.color_datattype"
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- 'color' is aliased to 'int' as a datatype to represent ARGB packed
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into a single int, commonly used in p5 for pixels[] and other color
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operations. this is just a search/replace type thing, and it can be
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used interchangeably with int.
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"compiler.web_colors" (currently "inline_web_colors")
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- color c = #cc0080; should unpack to 0xffcc0080 (the ff at the top is
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so that the color is opaque), which is just an int.
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Other preprocessor functionality
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- detects what 'mode' the program is in: static (no function brackets
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at all, just assumes everything is in draw), active (setup plus draw
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or loop), and java mode (full java support).
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http://proce55ing.net/reference/environment/index.html
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- size and background are pulled from draw mode programs and placed
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into setup(). this has a problem if size() is based on a variable,
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which we try to avoid people doing, but would like to be able to
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support it (perhaps by requiring the size() to be final?)
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- currently does a godawful scrambling of the comments so that the
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substitution doesn't try to run on them. this also causes lots of
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bizarro bugs.
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Possible?
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- would be nice to just type code wherever, mixing a 'static' style
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app with a few functions. would be simpler for starting out. but it
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seems that the declarations would have to be pulled out, but that
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all seems problematic. or maybe it could all be inside a static { }
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block. but that wouldn't seem to work either.
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