index.js

'use strict'

const keywords = require('./keywords')
const escapeHtml = require('./escapeHtml')

const DEFAULT_OPTIONS = {
  html: false,
  htmlEscaper: escapeHtml,
  classPrefix: 'sql-hl-',
  colors: {
    keyword: '\x1b[35m',
    function: '\x1b[31m',
    number: '\x1b[32m',
    string: '\x1b[32m',
    identifier: '\x1b[0m',
    special: '\x1b[33m',
    bracket: '\x1b[33m',
    comment: '\x1b[2m\x1b[90m',
    clear: '\x1b[0m'
  }
}

const highlighters = [
  /\b(?<number>\d+(?:\.\d+)?)\b/,

  // Note: Repeating string escapes like 'sql''server' will also work as they are just repeating strings
  /(?<string>'(?:[^'\\]|\\.)*'|"(?:[^"\\]|\\.)*")/,

  /(?<comment>--[^\n\r]*|#[^\n\r]*|\/\*(?:[^*]|\*(?!\/))*\*\/)/,

  // Future improvement: Comments should be allowed between the function name and the opening parenthesis
  /\b(?<function>\w+)(?=\s*\()/,

  /(?<bracket>[()])/,

  /(?<special>!=|[=%*/\-+,;:<>.])/,

  /(?<identifier>\b\w+\b|`(?:[^`\\]|\\.)*`)/,

  /(?<whitespace>\s+)/,

  /(?<unknown>\.+?)/
]

// Regex of the shape /(?<token1>...)|(?<token2>...)|.../g
const tokenizer = new RegExp(
  [
    '\\b(?<keyword>' + keywords.join('|') + ')\\b',
    ...highlighters.map(regex => regex.source)
  ].join('|'),
  'gis'
)

function getSegments (sqlString) {
  const segments = Array.from(sqlString.matchAll(tokenizer), match => ({
    name: Object.keys(match.groups).find(key => match.groups[key]),
    content: match[0]
  }))
  return segments
}

function highlight (sqlString, options) {
  options = Object.assign({}, DEFAULT_OPTIONS, options)

  return getSegments(sqlString)
    .map(({ name, content }) => {
      if (options.html) {
        const escapedContent = options.htmlEscaper(content)
        return name === 'whitespace' ? escapedContent : `<span class="${options.classPrefix}${name}">${escapedContent}</span>`
      }
      if (options.colors[name]) {
        return options.colors[name] + content + options.colors.clear
      }
      return content
    })
    .join('')
}

module.exports = {
  getSegments,
  highlight,
  DEFAULT_OPTIONS
}