COP 5021 Lecture -*- Outline -*-

* Overview of XText

** What is XText?
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         XTEXT OVERVIEW

XText is a framework for building DSLs

It has built-in ways to do:
   - lexical analysis
   - parsing
   - AST validation
   - Code generation (or interpretation)

Integrated with Xtend, an extension of Java
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    Q: What is an AST?
    An Abstract Syntax Tree

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 ABSTRACT SYNTAX TREES = OBJECT STRUCTURES

  input:
           x := x+1

  AST:

    [AssignS | v: * | aexp: * | label: * ]
                 /          |
                v  [AExpression | left: * | op: * | right: * ]
   [EString | * ]                      /        |          |
              |                       v         v          v
              v    [VarRefExpr | vname:  ]     "+" [NumLitExp | num: * ]
  [String | 1 | * ]                                                  |
               /                                                     v
              v                                                      1
[CharBuf | 'x' ]
               
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** basic tool usage
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        TYPICAL USAGE OF THE TOOLS

0. Create an XText project
     choose language name, file suffix, etc.

1. Create Lang.xtext in src folder

2. Generate XText artifacts
     right click on the .xtext file,
     select Run As...
       select Generate XText Artifacts

3. Run as Eclipse application to test
     right click on the main project
        (edu.ucf.cs.whilelang.WhileLang)
     select Run As...
        select Eclipse Application
   and/or run JUnit tests
     right click on the ....tests project
     select Run As...
        select JUnit Test

4. Edit to enhance the language

5. Repeat the above...

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          5 PROJECTS

for the language named "WhileLang"

edu.ucf.cs.whilelang.WhileLang
  > src
    > edu.ucf.cs.whilelang
      > WhileLang.xtext
      > ...
    > edu.ucf.cs.whilelang.generator
      > WhileLangGenerator.xtend
      > ...
    > edu.ucf.cs.whilelang.validation
      > WhileLangValidator.xtend
      > ...
  > ...

edu.ucf.cs.whilelang.WhileLang.ide

edu.ucf.cs.whilelang.WhileLang.tests
  > src
    > edu.ucf.cs.whilelang.tests
      > ...

edu.ucf.cs.whilelang.WhileLang.ui

edu.ucf.cs.whilelang.WhileLang.ui.tests

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    Q: What converts the user's input into an AST?
    The parser
    
** installation
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   INSTALLATION OF XTEXT TO FOLLOW ALONG

1. Install Java (8 or 9)
   http://www.oracle.com/technetwork/java/index.html
   (download Java SE)

2. Install Eclipse
   http://www.eclipse.org/downloads/packages/
     eclipse-ide-java-and-dsl-developers/oxygen2
   (use the package for Java and DSL Developers,
    which includes XText and XTend)

   or search the Eclipse Marketplace for XText
      and install that
      and add org.eclipse.xtext to required bundles

3. Install Eclipse Plug-in Development Environment (PDE)
   search the Marketplace

4. Clone the WhileLang project from Github
   git clone https://github.com/leavens/WhileLang.git

   in Eclipse
      File > Import ...
         select Git, clone URI
         import modules as subprojects
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    if necessary, change the JRE System Library to Alternate JRE
      by changing the buildpath settings in each project
          right click on project
               select Properties
               select Libraries
                  remove JRE System Lib from the list
                  then add it back with Add Library
                      select JRE System Library
                      select alternate JRE

     I also changed access restriction errors into warnings