antlr4

Trouble Setting Up ANTLR 4 IDE on Eclipse Luna (4.4)

由 我的梦境 提交于 2019-11-27 01:51:38
问题 I'm trying to install the ANTLR 4 IDE on Eclipse Luna (4.4). I've installed it from the Marketplace but I have no idea how to create a project that has an ANTLR 4 Lexer/Parser in it. When I go to create a new project I don't see any options for ANTLR 4. I tried creating a .g4 file and it opens in the editor but when I save it doesn't do anything. 回答1: I looked around all over the internet and found a handful of resources that I cobbled together and found a solution by trial and error. Below

ANTLR4 visitor pattern on simple arithmetic example

由 左心房为你撑大大i 提交于 2019-11-26 22:53:47
问题 I am a complete ANTLR4 newbie, so please forgive my ignorance. I ran into this presentation where a very simple arithmetic expression grammar is defined. It looks like: grammar Expressions; start : expr ; expr : left=expr op=('*'|'/') right=expr #opExpr | left=expr op=('+'|'-') right=expr #opExpr | atom=INT #atomExpr ; INT : ('0'..'9')+ ; WS : [ \t\r\n]+ -> skip ; Which is great because it will generate a very simple binary tree that can be traversed using the visitor pattern as explained in

ANTLR 4.5 - Mismatched Input 'x' expecting 'x'

由 佐手、 提交于 2019-11-26 18:02:10
问题 I have been starting to use ANTLR and have noticed that it is pretty fickle with its lexer rules. An extremely frustrating example is the following: grammar output; test: FILEPATH NEWLINE TITLE ; FILEPATH: ('A'..'Z'|'a'..'z'|'0'..'9'|':'|'\\'|'/'|' '|'-'|'_'|'.')+ ; NEWLINE: '\r'? '\n' ; TITLE: ('A'..'Z'|'a'..'z'|' ')+ ; This grammar will not match something like: c:\test.txt x Oddly if I change TITLE to be TITLE: 'x' ; it still fails this time giving an error message saying "mismatched input

How can I build an AST using ANTLR4? [duplicate]

由 一个人想着一个人 提交于 2019-11-26 17:50:56
问题 This question already has answers here : How to create AST with ANTLR4? (2 answers) Closed last year . I have an ANTLR3 grammar that builds an abstract syntax tree. I'm looking into upgrading to ANTLR4. However, it appears that ANTLR4 only builds parse trees and not abstract syntax trees. For example, the output=AST option is no longer recognized. Furthermore neither "AST" nor "abstract syntax" appears in the text of "The Definitive ANTLR4 reference" . I'm wondering if I'm missing something.

Allow Whitespace sections ANTLR4

由 只谈情不闲聊 提交于 2019-11-26 14:33:23
问题 I have an antlr4 grammar designed for an a domain specific language that is embedded into a text template. There are two modes: Text (whitespace should be preserved) Code (whitespace should be ignored) Sample grammar part: template : '{' templateBody '}' ; templateBody : templateChunk* ; templateChunk : code # codeChunk // dsl code, ignore whitespace | text # textChunk // any text, preserve whitespace ; The rule for code may contain a nested reference to the template rule. So the parser must

Antlr 4.5 parser error during runtime

由 随声附和 提交于 2019-11-26 12:33:21
问题 I\'m building simple grammar for programming laguange for learning purposes. I run into strange error that make no sense to me. line 1:0 missing {\'void\', \'int\', \'bool\', \'string\', \'union\'} at \'void\' I\'m using prebuild lexer and parser from this grammar: grammar ProgrammingLanguage; function_definition : type_specifier IDENTIFIER \'(\' parameter_list_opt \')\' compound_statement ; type_specifier : VOID | INT | BOOL | STRING | UNION ; compound_statement : \'{\' declaration_list

Handling errors in ANTLR4

由 耗尽温柔 提交于 2019-11-26 10:24:56
问题 The default behavior when the parser doesn\'t know what to do is to print messages to the terminal like: line 1:23 missing DECIMAL at \'}\' This is a good message, but in the wrong place. I\'d rather receive this as an exception. I\'ve tried using the BailErrorStrategy , but this throws a ParseCancellationException without a message (caused by a InputMismatchException , also without a message). Is there a way I can get it to report errors via exceptions while retaining the useful info in the

How does the ANTLR lexer disambiguate its rules (or why does my parser produce “mismatched input” errors)?

由 旧巷老猫 提交于 2019-11-26 06:48:05
问题 Note: This is a self-answered question that aims to provide a reference about one of the most common mistakes made by ANTLR users. When I test this very simple grammar: grammar KeyValues; keyValueList: keyValue*; keyValue: key=IDENTIFIER \'=\' value=INTEGER \';\'; IDENTIFIER: [A-Za-z0-9]+; INTEGER: [0-9]+; WS: [ \\t\\r\\n]+ -> skip; With the following input: foo = 42; I end up with the following run-time error: line 1:6 mismatched input \'42\' expecting INTEGER line 1:8 mismatched input \';\'

If/else statements in ANTLR using listeners

由 断了今生、忘了曾经 提交于 2019-11-26 06:18:00
I'm creating a simple programming language for a school project. I'm using ANTLR 4 to generate a lexer and a parser from my grammar. Until now, I have been using ANTLRs listener pattern to apply the actual functionality of the programming language. Now I would like to implement if/else statements but I'm not sure that these can actually be implemented when using the listener pattern as ANTLR decides in which order to traverse the parse tree when using listeners and I imagine that the implementation of if/else statements will require jumping around the parse tree depending on which condition in

If/else statements in ANTLR using listeners

由 ε祈祈猫儿з 提交于 2019-11-26 03:26:06
问题 I\'m creating a simple programming language for a school project. I\'m using ANTLR 4 to generate a lexer and a parser from my grammar. Until now, I have been using ANTLRs listener pattern to apply the actual functionality of the programming language. Now I would like to implement if/else statements but I\'m not sure that these can actually be implemented when using the listener pattern as ANTLR decides in which order to traverse the parse tree when using listeners and I imagine that the
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