json-query/index.js

Retrieves values from JSON objects for data binding. Offers params, nested queries, deep queries, custom reduce/filter functions and simple boolean logic. Browserify compatible.

var State = require('./lib/state')
var tokenize = require('./lib/tokenize')

var tokenizedCache = {}

module.exports = function jsonQuery (query, options) {

  // extract params for ['test[param=?]', 'value'] type queries
  var params = options && options.params || null
  if (Array.isArray(query)) {
    params = query.slice(1)
    query = query[0]
  }

  if (!tokenizedCache[query]) {
    tokenizedCache[query] = tokenize(query, true)
  }

  return handleQuery(tokenizedCache[query], options, params)
}


module.exports.lastParent = function (query) {
  var last = query.parents[query.parents.length - 1]
  if (last) {
    return last.value
  } else {
    return null
  }
}


function handleQuery (tokens, options, params) {
  var state = new State(options, params, handleQuery)

  for (var i = 0; i < tokens.length; i++) {
    if (handleToken(tokens[i], state)) {
      break
    }
  }

  // flush
  handleToken(null, state)

  // set databind hooks
  if (state.currentItem instanceof Object) {
    state.addReference(state.currentItem)
  } else {
    var parentObject = getLastParentObject(state.currentParents)
    if (parentObject) {
      state.addReference(parentObject)
    }
  }

  return {
    value: state.currentItem,
    key: state.currentKey,
    references: state.currentReferences,
    parents: state.currentParents
  }
}

function handleToken (token, state) {
  // state: setCurrent, getValue, getValues, resetCurrent, deepQuery, rootContext, currentItem, currentKey, options, filters

  if (token == null) {
    // process end of query
    if (!state.currentItem && state.options.force) {
      state.force(state.options.force)
    }
  } else if (token.values) {
    if (state.currentItem) {
      var keys = Object.keys(state.currentItem)
      var values = []
      keys.forEach(function (key) {
        if (token.deep && Array.isArray(state.currentItem[key])) {
          state.currentItem[key].forEach(function (item) {
            values.push(item)
          })
        } else {
          values.push(state.currentItem[key])
        }
      })
      state.setCurrent(keys, values)
    } else {
      state.setCurrent(keys, [])
    }
  } else if (token.get) {
    var key = state.getValue(token.get)
    if (shouldOverride(state, key)) {
      state.setCurrent(key, state.override[key])
    } else {
      if (state.currentItem || (state.options.force && state.force({}))) {
        if (isDeepAccessor(state.currentItem, key) || token.multiple) {
          var values = state.currentItem.map(function (item) {
            return item[key]
          }).filter(isDefined)

          values = Array.prototype.concat.apply([], values) // flatten

          state.setCurrent(key, values)
        } else {
          state.setCurrent(key, state.currentItem[key])
        }
      } else {
        state.setCurrent(key, null)
      }
    }
  } else if (token.select) {
    if (Array.isArray(state.currentItem) || (state.options.force && state.force([]))) {
      var match = (token.boolean ? token.select : [token]).map(function (part) {
        if (part.op === ':') {
          var key = state.getValue(part.select[0])
          return {
            func: function (item) {
              if (key) {
                item = item[key]
              }
              return state.getValueFrom(part.select[1], item)
            },
            negate: part.negate,
            booleanOp: part.booleanOp
          }
        } else {
          var selector = state.getValues(part.select)
          if (!state.options.allowRegexp && part.op === '~' && selector[1] instanceof RegExp) throw new Error('options.allowRegexp is not enabled.')
          return {
            key: selector[0],
            value: selector[1],
            negate: part.negate,
            booleanOp: part.booleanOp,
            op: part.op
          }
        }
      })

      if (token.multiple) {
        var keys = []
        var value = []
        state.currentItem.forEach(function (item, i) {
          if (matches(item, match)) {
            keys.push(i)
            value.push(item)
          }
        })
        state.setCurrent(keys, value)
      } else {
        if (!state.currentItem.some(function (item, i) {
          if (matches(item, match)) {
            state.setCurrent(i, item)
            return true
          }
        })) {
          state.setCurrent(null, null)
        }
      }
    } else {
      state.setCurrent(null, null)
    }
  } else if (token.root) {
    state.resetCurrent()
    if (token.args && token.args.length) {
      state.setCurrent(null, state.getValue(token.args[0]))
    } else {
      state.setCurrent(null, state.rootContext)
    }
  } else if (token.parent) {
    state.resetCurrent()
    state.setCurrent(null, state.options.parent)
  } else if (token.or) {
    if (state.currentItem) {
      return true
    } else {
      state.resetCurrent()
      state.setCurrent(null, state.context)
    }
  } else if (token.filter) {
    var helper = state.getLocal(token.filter) || state.getGlobal(token.filter)
    if (typeof helper === 'function') {
      // function(input, args...)
      var values = state.getValues(token.args || [])
      var result = helper.apply(state.options, [state.currentItem].concat(values))
      state.setCurrent(null, result)
    } else {
      // fallback to old filters
      var filter = state.getFilter(token.filter)
      if (typeof filter === 'function') {
        var values = state.getValues(token.args || [])
        var result = filter.call(state.options, state.currentItem, {args: values, state: state, data: state.rootContext})
        state.setCurrent(null, result)
      }
    }
  } else if (token.deep) {
    if (state.currentItem) {
      if (token.deep.length === 0) {
        return
      }

      var result = state.deepQuery(state.currentItem, token.deep, state.options)
      if (result) {
        state.setCurrent(result.key, result.value)
        for (var i = 0; i < result.parents.length; i++) {
          state.currentParents.push(result.parents[i])
        }
      } else {
        state.setCurrent(null, null)
      }
    } else {
      state.currentItem = null
    }
  }
}

function matches (item, parts) {
  var result = false
  for (var i = 0; i < parts.length; i++) {
    var opts = parts[i]
    var r = false
    if (opts.func) {
      r = opts.func(item)
    } else if (opts.op === '~') {
      if (opts.value instanceof RegExp) {
        r = item[opts.key] && !!item[opts.key].match(opts.value)
      } else {
        r = item[opts.key] && !!~item[opts.key].indexOf(opts.value)
      }
    } else if (opts.op === '=') {
      if ((item[opts.key] === true && opts.value === 'true') || (item[opts.key] === false && opts.value === 'false')) {
        r = true
      } else {
        r = item[opts.key] == opts.value
      }
    } else if (opts.op === '>') {
      r = item[opts.key] > opts.value
    } else if (opts.op === '<') {
      r = item[opts.key] < opts.value
    } else if (opts.op === '>=') {
      r = item[opts.key] >= opts.value
    } else if (opts.op === '<=') {
      r = item[opts.key] <= opts.value
    }

    if (opts.negate) {
      r = !r
    }
    if (opts.booleanOp === '&') {
      result = result && r
    } else if (opts.booleanOp === '|') {
      result = result || r
    } else {
      result = r
    }
  }

  return result
}

function isDefined(value) {
  return typeof value !== 'undefined'
}

function shouldOverride (state, key) {
  return state.override && state.currentItem === state.rootContext && state.override[key] !== undefined
}

function isDeepAccessor (currentItem, key) {
  return currentItem instanceof Array && parseInt(key) != key
}

function getLastParentObject (parents) {
  for (var i = 0; i < parents.length; i++) {
    if (!(parents[i + 1]) || !(parents[i + 1].value instanceof Object)) {
      return parents[i].value
    }
  }
}