- GOLD (parser)
Infobox_Software
name = GOLD Parsing System
caption =
developer = Devin Cook &
[http://www.devincook.com/goldparser/contributors Multiple Contributors]
latest_release_date =2007-07-29
latest_release_version = 3.4.4
operating_system = Windows
operating_system_desc = Windows 32-bit
genre =Parsers - LALR
license =Freeware &Open Source
website = [http://www.devincook.com/goldparser www.DevinCook/goldparser]GOLD is a freeware
parsing system that was designed to support multiple programming languages.Design
The system uses a DFA for lexical analysis and the
LALR algorithm for parsing. Both of these algorithms are state machines that use tables to determine actions. GOLD is designed around the principle of logically separating the process of generating theLALR and DFA parse tables from the actual implementation of the parsing algorithms themselves. This allows parsers to be implemented in different programming languages while maintaining the same grammars and development process.The GOLD system consists of three logical components, the "Builder", the "Engine", and a "Compiled Grammar Table" file type which functions as an intermediary between the first two.
Builder
The Builder is the primary component and main application of the system. The Builder is used to analyze the syntax of a language (specified in a grammar) and construct
LALR and DFA tables. During this process, any ambiguities in the grammar will be reported as a conflict. This is essentially the same task that is performed by compiler-compilers such asYACC andANTLR .Once the
LALR and DFA parse tables are successfully constructed, the Builder can save this data into a Compiled Grammar Table file. This allows the information to be reopened later by the Builder or used in one of the Engines. Currently, the Builder component is only available for Windows 32-bit operating systems.Some of the features of the Builder are as follows:
*
Freeware license
* State Browsing
* Integrated Testing
* Test multiple files wizard
* Generate Webpages (including hyperlinked syntax charts)
* Generate skeleton programs using templates
* Export grammars toYACC
* Export tables to XML or formatted textCompiled Grammar Table File
The Compiled Grammar Table file is used to store table information generated by the Builder.
Engine
Unlike the Builder, which is dependent on a single platform, the Engine component is written for a specific programming language and/or development platform. The Engine implements the
LALR and DFA algorithms. Since different programming languages use different approaches to designing programs, each implementation of the Engine will vary. As a result, an implementation of the Engine written forVisual Basic 6 will differ greatly from one written forANSI C .Currently, the following programming languages are supported by GOLD. Any language can be implemented by translating the existing source code.
* Assembly - Intel x86
*ANSI C
* C#
* D
* Delphi
* Java
* Pascal
* Python
*Visual Basic
*Visual Basic .NET
*Visual C++ Grammars
GOLD grammars are based directly on
Backus-Naur Form ,regular expression s, and set notation.The following grammar defines the syntax for a minimal general-purpose programming language called "Simple".
"Name" = 'Simple'"Author" = 'Devin Cook'"Version" = '2.1' "About" = 'This is a very simple grammar designed for use in examples'"Case Sensitive" = False "Start Symbol" =
{String Ch 1} = {Printable} - ["] {String Ch 2} = {Printable} - ["]
Identifier = {Letter}{AlphaNumeric}*
! String allows either single or double quotes
StringLiteral = " {String Ch 1}* "
'"' {String Ch 2}* '"'NumberLiteral = {Number}+('.'{Number}+)?
Comment Start = '/*'Comment End = '*/'Comment Line = '//'
::=
::= display
displayread ID
assign ID '='
whiledo end
ifthen end
ifthen else end ::= '>'
'<'
'<='
'>='
'='
'<>'
::= '+'
'-'
'&'
::= '*'
'/'
::= '-'
::= Identifier
StringLiteral
NumberLiteral
'('')' Development Overview
Design the Grammar
The first step consists of writing and testing a grammar for the language being parsed. The grammar can be written using any text editor - such as Notepad or the editor that is built into the Builder. At this stage, no coding is required.
Construct the Tables
Once the grammar is complete, it is analyzed by the Builder, the
LALR and DFA parse tables are constructed, and any ambiguities or problems with the grammar are reported. Afterwards, the tables are saved to a Compiled Grammar Table file to be used later by a parsing engine. At this point, the GOLD Parser Builder is no longer needed.elect a Parsing Engine
In the final stage, the tables are read by an Engine. At this point, the development process is dependent on the selected implementation language.
External links
* [http://www.devincook.com/goldparser/ GOLD Parsing System Homepage]
* [http://www.devincook.com/goldparser/contributors List of Contributors]
* [http://tech.groups.yahoo.com/group/goldparser/ GOLD Yahoo Group]
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