parser.spec.ts

import { describe, expect, it } from 'vitest'
import { NodeTypes } from './ast'
import { parser } from './parser'
import { TokenTypes } from './tokenizer'

describe('parser', () => {
  it('parser tokens to ast', () => {
    const tokens = [
      { type: TokenTypes.Paren, value: '(' },
      { type: TokenTypes.Name, value: 'add' },
      { type: TokenTypes.Number, value: '2' },
      { type: TokenTypes.Paren, value: '(' },
      { type: TokenTypes.Name, value: 'subtract' },
      { type: TokenTypes.Number, value: '4' },
      { type: TokenTypes.Number, value: '2' },
      { type: TokenTypes.Paren, value: ')' },
      { type: TokenTypes.Paren, value: ')' },
    ]
    const ast = {
      type: NodeTypes.Program,
      body: [
        {
          type: NodeTypes.CallExpression,
          name: 'add',
          params: [
            {
              type: NodeTypes.NumberLiteral,
              value: '2',
            },
            {
              type: NodeTypes.CallExpression,
              name: 'subtract',
              params: [
                {
                  type: NodeTypes.NumberLiteral,
                  value: '4',
                },
                {
                  type: NodeTypes.NumberLiteral,
                  value: '2',
                },
              ],
            },
          ],
        },
      ],
    }
    expect(parser(tokens)).toEqual(ast)
  })

  it('number', () => {
    const tokens = [{ type: TokenTypes.Number, value: '2' }]

    const ast = {
      type: NodeTypes.Program,
      body: [
        {
          type: NodeTypes.NumberLiteral,
          value: '2',
        },
      ],
    }
    expect(parser(tokens)).toEqual(ast)
  })

  it('name', () => {
    const tokens = [{ type: TokenTypes.String, value: 'hello' }]

    const ast = {
      type: NodeTypes.Program,
      body: [
        {
          type: NodeTypes.StringLiteral,
          value: 'hello',
        },
      ],
    }
    expect(parser(tokens)).toEqual(ast)
  })

  it('call expression (add 1 1)', () => {
    const tokens = [
      { type: TokenTypes.Paren, value: '(' },
      { type: TokenTypes.Name, value: 'add' },
      { type: TokenTypes.Number, value: '1' },
      { type: TokenTypes.Number, value: '1' },
      { type: TokenTypes.Paren, value: ')' },
    ]
    const ast = {
      type: NodeTypes.Program,
      body: [
        {
          type: NodeTypes.CallExpression,
          name: 'add',
          params: [
            {
              type: NodeTypes.NumberLiteral,
              value: '1',
            },
            {
              type: NodeTypes.NumberLiteral,
              value: '1',
            },
          ],
        },
      ],
    }

    expect(parser(tokens)).toEqual(ast)
  })
})