index.js

var attrToProp = require('hyperscript-attribute-to-property')

var VAR = 0, TEXT = 1, OPEN = 2, CLOSE = 3, ATTR = 4
var ATTR_KEY = 5, ATTR_KEY_W = 6
var ATTR_VALUE_W = 7, ATTR_VALUE = 8
var ATTR_VALUE_SQ = 9, ATTR_VALUE_DQ = 10
var ATTR_EQ = 11, ATTR_BREAK = 12

module.exports = function (h, opts) {
  h = attrToProp(h)
  if (!opts) opts = {}
  var concat = opts.concat || function (a, b) {
    return String(a) + String(b)
  }

  return function (strings) {
    var state = TEXT, reg = ''
    var arglen = arguments.length
    var parts = []

    for (var i = 0; i < strings.length; i++) {
      if (i < arglen - 1) {
        var arg = arguments[i+1]
        var p = parse(strings[i])
        var xstate = state
        if (xstate === ATTR_VALUE_DQ) xstate = ATTR_VALUE
        if (xstate === ATTR_VALUE_SQ) xstate = ATTR_VALUE
        if (xstate === ATTR_VALUE_W) xstate = ATTR_VALUE
        if (xstate === ATTR) xstate = ATTR_KEY
        p.push([ VAR, xstate, arg ])
        parts.push.apply(parts, p)
      } else parts.push.apply(parts, parse(strings[i]))
    }

    var tree = [null,{},[]]
    var stack = [[tree,-1]]
    for (var i = 0; i < parts.length; i++) {
      var cur = stack[stack.length-1][0]
      var p = parts[i], s = p[0]
      if (s === OPEN && /^\//.test(p[1])) {
        var ix = stack[stack.length-1][1]
        if (stack.length > 1) {
          stack.pop()
          stack[stack.length-1][0][2][ix] = h(
            cur[0], cur[1], cur[2].length ? cur[2] : undefined
          )
        }
      } else if (s === OPEN) {
        var c = [p[1],{},[]]
        cur[2].push(c)
        stack.push([c,cur[2].length-1])
      } else if (s === ATTR_KEY || (s === VAR && p[1] === ATTR_KEY)) {
        var key = ''
        var copyKey
        for (; i < parts.length; i++) {
          if (parts[i][0] === ATTR_KEY) {
            key = concat(key, parts[i][1])
          } else if (parts[i][0] === VAR && parts[i][1] === ATTR_KEY) {
            if (typeof parts[i][2] === 'object' && !key) {
              for (copyKey in parts[i][2]) {
                if (parts[i][2].hasOwnProperty(copyKey) && !cur[1][copyKey]) {
                  cur[1][copyKey] = parts[i][2][copyKey]
                }
              }
            } else {
              key = concat(key, parts[i][2])
            }
          } else break
        }
        if (parts[i][0] === ATTR_EQ) i++
        var j = i
        for (; i < parts.length; i++) {
          if (parts[i][0] === ATTR_VALUE || parts[i][0] === ATTR_KEY) {
            if (!cur[1][key]) cur[1][key] = strfn(parts[i][1])
            else cur[1][key] = concat(cur[1][key], parts[i][1])
          } else if (parts[i][0] === VAR
          && (parts[i][1] === ATTR_VALUE || parts[i][1] === ATTR_KEY)) {
            if (!cur[1][key]) cur[1][key] = strfn(parts[i][2])
            else cur[1][key] = concat(cur[1][key], parts[i][2])
          } else {
            if (key.length && !cur[1][key] && i === j
            && (parts[i][0] === CLOSE || parts[i][0] === ATTR_BREAK)) {
              // https://html.spec.whatwg.org/multipage/infrastructure.html#boolean-attributes
              // empty string is falsy, not well behaved value in browser
              cur[1][key] = key.toLowerCase()
            }
            break
          }
        }
      } else if (s === ATTR_KEY) {
        cur[1][p[1]] = true
      } else if (s === VAR && p[1] === ATTR_KEY) {
        cur[1][p[2]] = true
      } else if (s === CLOSE) {
        if (selfClosing(cur[0]) && stack.length) {
          var ix = stack[stack.length-1][1]
          stack.pop()
          stack[stack.length-1][0][2][ix] = h(
            cur[0], cur[1], cur[2].length ? cur[2] : undefined
          )
        }
      } else if (s === VAR && p[1] === TEXT) {
        if (p[2] === undefined || p[2] === null) p[2] = ''
        else if (!p[2]) p[2] = concat('', p[2])
        if (Array.isArray(p[2][0])) {
          cur[2].push.apply(cur[2], p[2])
        } else {
          cur[2].push(p[2])
        }
      } else if (s === TEXT) {
        cur[2].push(p[1])
      } else if (s === ATTR_EQ || s === ATTR_BREAK) {
        // no-op
      } else {
        throw new Error('unhandled: ' + s)
      }
    }

    if (tree[2].length > 1 && /^\s*$/.test(tree[2][0])) {
      tree[2].shift()
    }

    if (tree[2].length > 2
    || (tree[2].length === 2 && /\S/.test(tree[2][1]))) {
      throw new Error(
        'multiple root elements must be wrapped in an enclosing tag'
      )
    }
    if (Array.isArray(tree[2][0]) && typeof tree[2][0][0] === 'string'
    && Array.isArray(tree[2][0][2])) {
      tree[2][0] = h(tree[2][0][0], tree[2][0][1], tree[2][0][2])
    }
    return tree[2][0]

    function parse (str) {
      var res = []
      if (state === ATTR_VALUE_W) state = ATTR
      for (var i = 0; i < str.length; i++) {
        var c = str.charAt(i)
        if (state === TEXT && c === '<') {
          if (reg.length) res.push([TEXT, reg])
          reg = ''
          state = OPEN
        } else if (c === '>' && !quot(state)) {
          if (state === OPEN) {
            res.push([OPEN,reg])
          } else if (state === ATTR_KEY) {
            res.push([ATTR_KEY,reg])
          } else if (state === ATTR_VALUE && reg.length) {
            res.push([ATTR_VALUE,reg])
          }
          res.push([CLOSE])
          reg = ''
          state = TEXT
        } else if (state === TEXT) {
          reg += c
        } else if (state === OPEN && /\s/.test(c)) {
          res.push([OPEN, reg])
          reg = ''
          state = ATTR
        } else if (state === OPEN) {
          reg += c
        } else if (state === ATTR && /[\w-]/.test(c)) {
          state = ATTR_KEY
          reg = c
        } else if (state === ATTR && /\s/.test(c)) {
          if (reg.length) res.push([ATTR_KEY,reg])
          res.push([ATTR_BREAK])
        } else if (state === ATTR_KEY && /\s/.test(c)) {
          res.push([ATTR_KEY,reg])
          reg = ''
          state = ATTR_KEY_W
        } else if (state === ATTR_KEY && c === '=') {
          res.push([ATTR_KEY,reg],[ATTR_EQ])
          reg = ''
          state = ATTR_VALUE_W
        } else if (state === ATTR_KEY) {
          reg += c
        } else if ((state === ATTR_KEY_W || state === ATTR) && c === '=') {
          res.push([ATTR_EQ])
          state = ATTR_VALUE_W
        } else if ((state === ATTR_KEY_W || state === ATTR) && !/\s/.test(c)) {
          res.push([ATTR_BREAK])
          if (/[\w-]/.test(c)) {
            reg += c
            state = ATTR_KEY
          } else state = ATTR
        } else if (state === ATTR_VALUE_W && c === '"') {
          state = ATTR_VALUE_DQ
        } else if (state === ATTR_VALUE_W && c === "'") {
          state = ATTR_VALUE_SQ
        } else if (state === ATTR_VALUE_DQ && c === '"') {
          res.push([ATTR_VALUE,reg],[ATTR_BREAK])
          reg = ''
          state = ATTR
        } else if (state === ATTR_VALUE_SQ && c === "'") {
          res.push([ATTR_VALUE,reg],[ATTR_BREAK])
          reg = ''
          state = ATTR
        } else if (state === ATTR_VALUE_W && !/\s/.test(c)) {
          state = ATTR_VALUE
          i--
        } else if (state === ATTR_VALUE && /\s/.test(c)) {
          res.push([ATTR_VALUE,reg],[ATTR_BREAK])
          reg = ''
          state = ATTR
        } else if (state === ATTR_VALUE || state === ATTR_VALUE_SQ
        || state === ATTR_VALUE_DQ) {
          reg += c
        }
      }
      if (state === TEXT && reg.length) {
        res.push([TEXT,reg])
        reg = ''
      } else if (state === ATTR_VALUE && reg.length) {
        res.push([ATTR_VALUE,reg])
        reg = ''
      } else if (state === ATTR_VALUE_DQ && reg.length) {
        res.push([ATTR_VALUE,reg])
        reg = ''
      } else if (state === ATTR_VALUE_SQ && reg.length) {
        res.push([ATTR_VALUE,reg])
        reg = ''
      } else if (state === ATTR_KEY) {
        res.push([ATTR_KEY,reg])
        reg = ''
      }
      return res
    }
  }

  function strfn (x) {
    if (typeof x === 'function') return x
    else if (typeof x === 'string') return x
    else if (x && typeof x === 'object') return x
    else return concat('', x)
  }
}

function quot (state) {
  return state === ATTR_VALUE_SQ || state === ATTR_VALUE_DQ
}

var hasOwn = Object.prototype.hasOwnProperty
function has (obj, key) { return hasOwn.call(obj, key) }

var closeRE = RegExp('^(' + [
  'area', 'base', 'basefont', 'bgsound', 'br', 'col', 'command', 'embed',
  'frame', 'hr', 'img', 'input', 'isindex', 'keygen', 'link', 'meta', 'param',
  'source', 'track', 'wbr',
  // SVG TAGS
  'animate', 'animateTransform', 'circle', 'cursor', 'desc', 'ellipse',
  'feBlend', 'feColorMatrix', 'feComponentTransfer', 'feComposite',
  'feConvolveMatrix', 'feDiffuseLighting', 'feDisplacementMap',
  'feDistantLight', 'feFlood', 'feFuncA', 'feFuncB', 'feFuncG', 'feFuncR',
  'feGaussianBlur', 'feImage', 'feMergeNode', 'feMorphology',
  'feOffset', 'fePointLight', 'feSpecularLighting', 'feSpotLight', 'feTile',
  'feTurbulence', 'font-face-format', 'font-face-name', 'font-face-uri',
  'glyph', 'glyphRef', 'hkern', 'image', 'line', 'missing-glyph', 'mpath',
  'path', 'polygon', 'polyline', 'rect', 'set', 'stop', 'tref', 'use', 'view',
  'vkern'
].join('|') + ')(?:[\.#][a-zA-Z0-9\u007F-\uFFFF_:-]+)*$')
function selfClosing (tag) { return closeRE.test(tag) }