antlr/doc/faq/index.md

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2015-10-26 05:04:14 +08:00
# Frequently-Asked Questions
## Getting Started
* How to I install and run a simple grammar?
* Why does my parser test program hang?
## Installation
* Why can't ANTLR (grun) find my lexer or parser?
* Why can't I run the ANTLR tool?
* Why doesn't my parser compile?
## General
* Why do we need ANTLR v4?
* What is the difference between ANTLR 3 and 4?
* Why is my expression parser slow?
## Grammar syntax
## Lexical analysis
* How can I parse non-ASCII text and use characters in token rules?
* How do I replace escape characters in string tokens?
* Why are my keywords treated as identifiers?
* Why are there no whitespace tokens in the token stream?
## Parse Trees
* How do I get the input text for a parse-tree subtree?
* What if I need ASTs not parse trees for a compiler, for example?
* When do I use listener/visitor vs XPath vs Tree pattern matching?
## Translation
* ASTs vs parse trees
* Decoupling input walking from output generation
## Actions and semantic predicates
* How do I test if an optional rule was matched?
## Error handling
* How do I perform semantic checking with ANTLR?