sexp-template/src/lexer.js

const tokenTypes = {
  OPAREN: '(',
  CPAREN: ')',
  KEYWORD: 'keyword',
  QUOTE: '"',
  LITERAL: 'literal',
  ATTRIBUTE: 'attribute',
  EOF: 'eof',
}

const scan = source => {
  pos = 0
  line = 1
  tokens = []

  while (pos < source.length) {
    if (source[pos].match(/\(/)) {
      tokens.push({
        type: tokenTypes.OPAREN,
        line: line,
      })
      pos++
    } else if (source[pos].match(/\)/)) {
      tokens.push({
        type: tokenTypes.CPAREN,
        line: line,
      })
      pos++
    } else if (source[pos].match(/['"]/)) {
      tokens.push({
        type: tokenTypes.QUOTE,
        line: line,
      })
      pos++
    } else if (source[pos].match(/:/)) {
      let value = /:([^()'"\s]+)/.exec(source)[1].trim()
      tokens.push({
        type: tokenTypes.ATTRIBUTE,
        line: line,
        value: value,
      })
      pos += value.length + 1 // the +1 is to account for the colon
    } else if (source[pos].match(/\n/)) {
      line++
      pos++
    } else if (source[pos].match(/\s/)) {
      pos++
    } else {
      let value = /[^()"':]+/.exec(source.slice(pos))[0]
      tokens.push({
        type: tokenTypes.LITERAL,
        line: line,
        value: value.trim(),
      })
      pos += value.length
    }
  }

  tokens.push({
    type: tokenTypes.EOF,
    line: line,
  })
  return tokens
}

module.exports = {
  scan: scan,
  tokenTypes: tokenTypes,
}