README
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pg 
pg - toy parser generator.
Installation
% go get github.com/davidrjenni/pg/pg
Documentation
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Overview ¶
Package pg provides packages to lex, parse and pretty-print context-free grammars. Furthermore it provides a package for generating SLR(1) parsers. The command pg implements a parser generator using these packages. Package example contains example programs which use the command pg.
A grammar is specified using BNF, which is a set of derivation rules (productions). The following grammar specifies BNF (represented itself in BNF); any input must satisfy this grammar:
Production -> "PRODUCTION_NAME" "->" Expression "." . Expression -> Expression "|" Alternative | Alternative . Alternative -> Alternative Terminal | Terminal . Terminal -> "PRODUCTION_NAME" | "TOKEN" | "e" .
Production names and tokens are symbols of the grammar. The name of the first production of the grammar is the start symbol. A production name is an identifier, a token is a string. The arrow "->" is interchangeable with the UTF-8 character U+2192 "→". The symbol "e" indicates the empty symbol (epsilon). "e" is interchangeable with the UTF-8 character U+03B5 "ε".
The arrow means that the symbol on the left must be replaced with the expression on the right. An expression consists of one or more sequences of symbols. More sequences are separated by a vertical bar, indicating a choice. Multiple lines are allowed. A production is terminated by a dot. The arrow means that the symbol on the left must be replaced with the expression on the right.
Source Files
Directories
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| Path | Synopsis |
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Package ast declares the types used to represent syntax trees for pg.
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Package ast declares the types used to represent syntax trees for pg. |
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example
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calc
Command calc implements a calculator using pg.
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Command calc implements a calculator using pg. |
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Package generator implements a parser generator.
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Package generator implements a parser generator. |
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Package parser implements a parser for pg.
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Package parser implements a parser for pg. |
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pg is tool for managing context-free grammars.
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pg is tool for managing context-free grammars. |
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Package printer implements pretty-printing of AST nodes.
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Package printer implements pretty-printing of AST nodes. |
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Package scanner implements a scanner for pg.
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Package scanner implements a scanner for pg. |
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Package token defines constants representing the lexical tokens for pg.
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Package token defines constants representing the lexical tokens for pg. |