Compiler Basics

This repo contains four examples:

minus folder

• The first one in folder minus is a simple interpreter for infix arithmetic expressions with the minus operator only
  • See files minus.jison, minus.l and use_minus.js

location folder

• The example in folder location shows how to access to the location of tokens, how to pass information from outside to an action, how to deal with lexical errors and a few tricks to improve error messages
  • See files minus-error-management.jison, minus-error-management.l and main.js
  • The err.js file contains the error message function

➜  ast git:(master) ✗ npx jison minus-ast.jison  minus-ast.l -o minus.js

The file use-minus.js outputs the AST in JSON format:

➜  ast git:(master) ✗ cat use_minus.js 
#!/usr/bin/env node
const p = require("./minus").parser;

const t = p.parse(process.argv[2] || "2-1-1");
console.log(JSON.stringify(t, null, 2));

Here is an execution example:

➜  ast git:(master) ✗ ./use_minus.js > ast.json; cat ast.json     
{
  "type": "Program",
  "body": [
    {
      "type": "ExpressionStatement",
      "expression": {
        "type": "CallExpression",
        "callee": {
          "type": "MemberExpression",
          "object": {
            "type": "Identifier",
            "name": "console"
          },
          "property": {
            "type": "Identifier",
            "name": "log"
          },
          "computed": false
        },
        "arguments": [
          {
            "type": "BinaryExpression",
            "left": {
              "type": "BinaryExpression",
              "left": {
                "type": "Literal",
                "value": 2,
                "raw": "2"
              },
              "operator": "-",
              "right": {
                "type": "Literal",
                "value": 1,
                "raw": "1"
              }
            },
            "operator": "-",
            "right": {
              "type": "Literal",
              "value": 1,
              "raw": "1"
            }
          }
        ]
      }
    }
  ],
  "sourceType": "script"
}

ast folder

• The example in folder ast is a translator from infix arithmetic expressions to JavaScript
  • minus-ast.jison builds a Espree compatible AST using minus.l and the helpers in ast-build.js
  • Check astexplorer.net demo to explore the shape of the ASTs
  • The lexical analyzer minus.l is used by both examples
• The ast.json filescontain examples of Espree ASTs for console.log(2-1-1)

More details in ast/README.md

prec folder

• The example in folder prec illustrates the use of the %prec directive to resolve conflicts
  • See files prec.jison, prec.l and use_prec.js
  • The prec-*.json files contain examples of Espree ASTs

package.json scripts to run the examples

hello-jison git:(master) npm run
Lifecycle scripts included in hello-jison@1.0.0:
  test
    npm run tojs; node ast/salida.js

available via `npm run-script`:
  test-simple
    npm run build; ./minus/use_minus.js
  tojs
    npm run build-ast; ./ast/ast2js.js | tee ast/salida.js
  build-ast
    npm run compile-ast; ./ast/use_minus.js > ast/ast.json; cat ast/ast.json
  build
    jison minus/minus.jison minus/minus.l -o minus/minus.js
  loc
    jison location/minus-error-management.jison location/minus-error-management.l -o location/minus.js
  debug
    jison minus/minus.jison minus/minus.l -o minus/minus.js --debug
  dfa
    bison -v minus.jison; rm -f minus.tab.jison
  prec
    jison prec/uminus.jison prec/minus.l -o prec/uminus.js; prec/use-prec.js
  compile-ast
    jison ast/minus-ast.jison ast/minus-ast.l -o ast/minus.js
  clean
    rm -f ast/ast.json ast/salida.js ast/minus.js location/minus.js

Install the dependencies:

npm i

Branches

The landing branch:

• master

One branch per class yearmonthday:

• 20230213
• 20230214

Start to work from branch

• initial

References

• Repo ULL-ESIT-GRADOII-PL/esprima-pegjs-jsconfeu-talk
• crguezl/hello-jison
• Espree
  • Options for parse and tokenize methods
• astexplorer.net demo
• Jison Playground
• idgrep.js
• Introducción a los Compiladores con Jison y Espree
• Google Slides Intro to Compilers by Casiano