feat: promise support for drops, working on #65

src/builtin/tags/assign.ts

@@ -14,10 +14,9 @@ export default {
     this.key = match[1]
     this.value = match[2]
   },
-  render: function (scope: Scope) {
+  render: async function (scope: Scope) {
     const ctx = new AssignScope()
-    ctx[this.key] = this.liquid.evalValue(this.value, scope)
+    ctx[this.key] = await this.liquid.evalValue(this.value, scope)
     scope.push(ctx)
-    return Promise.resolve('')
   }
 } as ITagImplOptions

src/builtin/tags/case.ts

@@ -30,11 +30,11 @@ export default {
     stream.start()
   },
 
-  render: function (scope: Scope) {
+  render: async function (scope: Scope) {
     for (let i = 0; i < this.cases.length; i++) {
       const branch = this.cases[i]
-      const val = evalExp(branch.val, scope)
-      const cond = evalExp(this.cond, scope)
+      const val = await evalExp(branch.val, scope)
+      const cond = await evalExp(this.cond, scope)
       if (val === cond) {
         return this.liquid.renderer.renderTemplates(branch.templates, scope)
       }

src/builtin/tags/cycle.ts

@@ -24,8 +24,8 @@ export default <ITagImplOptions>{
     assert(this.candidates.length, `empty candidates: ${tagToken.raw}`)
   },
 
-  render: function (scope: Scope) {
-    const group = evalValue(this.group, scope)
+  render: async function (scope: Scope) {
+    const group = await evalValue(this.group, scope)
     const fingerprint = `cycle:${group}:` + this.candidates.join(',')
     const groups = scope.groups
     let idx = groups[fingerprint]

src/builtin/tags/for.ts

@@ -42,7 +42,7 @@ export default <ITagImplOptions>{
     stream.start()
   },
   render: async function (scope: Scope, hash: Hash) {
-    let collection = evalExp(this.collection, scope)
+    let collection = await evalExp(this.collection, scope)
 
     if (!isArray(collection)) {
       if (isString(collection) && collection.length > 0) {

src/builtin/tags/if.ts

@@ -33,9 +33,9 @@ export default {
     stream.start()
   },
 
-  render: function (scope: Scope) {
+  render: async function (scope: Scope) {
     for (const branch of this.branches) {
-      const cond = evalExp(branch.cond, scope)
+      const cond = await evalExp(branch.cond, scope)
       if (isTruthy(cond)) {
         return this.liquid.renderer.renderTemplates(branch.templates, scope)
       }

src/builtin/tags/include.ts

@@ -34,7 +34,7 @@ export default <ITagImplOptions>{
         const template = this.value.slice(1, -1)
         filepath = await this.liquid.parseAndRender(template, scope.getAll(), scope.opts)
       } else {
-        filepath = evalValue(this.value, scope)
+        filepath = await evalValue(this.value, scope)
       }
     } else {
       filepath = this.staticValue
@@ -47,7 +47,7 @@ export default <ITagImplOptions>{
     scope.blocks = {}
     scope.blockMode = BlockMode.OUTPUT
     if (this.with) {
-      hash[filepath] = evalValue(this.with, scope)
+      hash[filepath] = await evalValue(this.with, scope)
     }
     const templates = await this.liquid.getTemplate(filepath, scope.opts)
     scope.push(hash)

src/builtin/tags/layout.ts

@@ -26,7 +26,7 @@ export default {
   },
   render: async function (scope: Scope, hash: Hash) {
     const layout = scope.opts.dynamicPartials
-      ? evalValue(this.layout, scope)
+      ? await evalValue(this.layout, scope)
       : this.staticLayout
     assert(layout, `cannot apply layout with empty filename`)
 

src/builtin/tags/tablerow.ts

@@ -36,7 +36,7 @@ export default {
   },
 
   render: async function (scope: Scope, hash: Hash) {
-    let collection = evalExp(this.collection, scope) || []
+    let collection = await evalExp(this.collection, scope) || []
     const offset = hash.offset || 0
     const limit = (hash.limit === undefined) ? collection.length : hash.limit
 

src/builtin/tags/unless.ts

@@ -25,8 +25,8 @@ export default {
     stream.start()
   },
 
-  render: function (scope: Scope) {
-    const cond = evalExp(this.cond, scope)
+  render: async function (scope: Scope) {
+    const cond = await evalExp(this.cond, scope)
     return isFalsy(cond)
       ? this.liquid.renderer.renderTemplates(this.templates, scope)
       : this.liquid.renderer.renderTemplates(this.elseTemplates, scope)

src/drop/drop.ts

@@ -3,7 +3,7 @@ export abstract class Drop {
     return undefined
   }
 
-  liquidMethodMissing (key: string): string | undefined {
+  liquidMethodMissing (key: string): Promise<string | undefined> | string | undefined {
     return undefined
   }
 }

src/render/syntax.ts

@@ -48,36 +48,36 @@ const binaryOperators: {[key: string]: (lhs: any, rhs: any) => boolean} = {
   'or': (l: any, r: any) => isTruthy(l) || isTruthy(r)
 }
 
-export function parseExp (exp: string, scope: Scope): any {
+export async function parseExp (exp: string, scope: Scope): Promise<any> {
   assert(scope, 'unable to parseExp: scope undefined')
   const operatorREs = lexical.operators
   let match
   for (let i = 0; i < operatorREs.length; i++) {
     const operatorRE = operatorREs[i]
     const expRE = new RegExp(`^(${lexical.quoteBalanced.source})(${operatorRE.source})(${lexical.quoteBalanced.source})$`)
     if ((match = exp.match(expRE))) {
-      const l = parseExp(match[1], scope)
+      const l = await parseExp(match[1], scope)
       const op = binaryOperators[match[2].trim()]
-      const r = parseExp(match[3], scope)
+      const r = await parseExp(match[3], scope)
       return op(l, r)
     }
   }
 
   if ((match = exp.match(lexical.rangeLine))) {
-    const low = evalValue(match[1], scope)
-    const high = evalValue(match[2], scope)
-    return range(low, high + 1)
+    const low = await evalValue(match[1], scope)
+    const high = await evalValue(match[2], scope)
+    return range(+low, +high + 1)
   }
 
   return parseValue(exp, scope)
 }
 
-export function evalExp (str: string, scope: Scope): any {
-  const value = parseExp(str, scope)
+export async function evalExp (str: string, scope: Scope): Promise<any> {
+  const value = await parseExp(str, scope)
   return value instanceof Drop ? value.valueOf() : value
 }
 
-function parseValue (str: string | undefined, scope: Scope): any {
+async function parseValue (str: string | undefined, scope: Scope): Promise<any> {
   if (!str) return null
   str = str.trim()
 
@@ -91,8 +91,8 @@ function parseValue (str: string | undefined, scope: Scope): any {
   return scope.get(str)
 }
 
-export function evalValue (str: string | undefined, scope: Scope): any {
-  const value = parseValue(str, scope)
+export async function evalValue (str: string | undefined, scope: Scope) {
+  const value = await parseValue(str, scope)
   return value instanceof Drop ? value.valueOf() : value
 }
 

src/scope/context.ts

@@ -0,0 +1,10 @@
+import { Drop } from '../drop/drop'
+
+type PlainObject = {
+  [key: string]: any
+  liquid_method_missing?: (key: string) => any // eslint-disable-line
+  to_liquid?: () => any // eslint-disable-line
+  toLiquid?: () => any  // eslint-disable-line
+}
+
+export type Context = PlainObject | Drop

src/scope/scope.ts

@@ -4,13 +4,7 @@ import { __assign } from 'tslib'
 import assert from '../util/assert'
 import { NormalizedFullOptions, applyDefault } from '../liquid-options'
 import BlockMode from './block-mode'
-
-export type Context = {
-  [key: string]: any
-  liquid_method_missing?: (key: string) => any // eslint-disable-line
-  to_liquid?: () => any // eslint-disable-line
-  toLiquid?: () => any  // eslint-disable-line
-}
+import { Context } from './context'
 
 export default class Scope {
   opts: NormalizedFullOptions
@@ -25,19 +19,19 @@ export default class Scope {
   getAll () {
     return this.contexts.reduce((ctx, val) => __assign(ctx, val), {})
   }
-  get (path: string): any {
-    const paths = this.propertyAccessSeq(path)
-    const scope = this.findContextFor(paths[0]) || _.last(this.contexts)
-    return paths.reduce((value, key) => {
-      const val = this.readProperty(value, key)
-      if (_.isNil(val) && this.opts.strictVariables) {
-        throw new TypeError(`undefined variable: ${key}`)
+  async get (path: string) {
+    const paths = await this.propertyAccessSeq(path)
+    let ctx = this.findContextFor(paths[0]) || _.last(this.contexts)
+    for (let path of paths) {
+      ctx = this.readProperty(ctx, path)
+      if (_.isNil(ctx) && this.opts.strictVariables) {
+        throw new TypeError(`undefined variable: ${path}`)
       }
-      return val
-    }, scope)
+    }
+    return ctx
   }
-  set (path: string, v: any): void {
-    const paths = this.propertyAccessSeq(path)
+  async set (path: string, v: any) {
+    const paths = await this.propertyAccessSeq(path)
     let scope = this.findContextFor(paths[0]) || _.last(this.contexts)
     paths.some((key, i) => {
       if (!_.isObject(scope)) {
@@ -99,7 +93,7 @@ export default class Scope {
    * accessSeq("foo['b]r']")      // ['foo', 'b]r']
    * accessSeq("foo[bar.coo]")    // ['foo', 'bar'], for bar.coo == 'bar'
    */
-  propertyAccessSeq (str: string) {
+  async propertyAccessSeq (str: string) {
     str = String(str)
     const seq: string[] = []
     let name = ''
@@ -122,7 +116,7 @@ export default class Scope {
             assert(j !== -1, `unbalanced []: ${str}`)
             name = str.slice(i + 1, j)
             if (!/^[+-]?\d+$/.test(name)) { // foo[bar] vs. foo[1]
-              name = String(this.get(name))
+              name = String(await this.get(name))
             }
             push()
             i = j + 1
@@ -152,9 +146,9 @@ export default class Scope {
 }
 
 function readSize (obj: Context) {
-  if (!_.isNil(obj.size)) return obj.size
+  if (!_.isNil(obj['size'])) return obj['size']
   if (_.isArray(obj) || _.isString(obj)) return obj.length
-  return obj.size
+  return obj['size']
 }
 
 function matchRightBracket (str: string, begin: number) {

src/template/filter/filter.ts

@@ -19,9 +19,13 @@ export class Filter {
     this.impl = impl || (x => x)
     this.args = args
   }
-  render (value: any, scope: Scope): any {
-    const args = this.args.map(arg => isArray(arg) ? [arg[0], evalValue(arg[1], scope)] : evalValue(arg, scope))
-    return this.impl.apply(null, [value, ...args])
+  async render (value: any, scope: Scope) {
+    const argv: any[] = []
+    for(let arg of this.args) {
+      if (isArray(arg)) argv.push([arg[0], await evalValue(arg[1], scope)])
+      else argv.push(await evalValue(arg, scope))
+    }
+    return this.impl.apply(null, [value, ...argv])
   }
   static register (name: string, filter: FilterImpl) {
     Filter.impls[name] = filter

src/template/tag/hash.ts

@@ -10,13 +10,15 @@ import Scope from '../../scope/scope'
  */
 export default class Hash {
   [key: string]: any
-  constructor (markup: string, scope: Scope) {
+  static async create (markup: string, scope: Scope) {
+    const instance = new Hash()
     let match
     hashCapture.lastIndex = 0
     while ((match = hashCapture.exec(markup))) {
       const k = match[1]
       const v = match[2]
-      this[k] = evalValue(v, scope)
+      instance[k] = await evalValue(v, scope)
     }
+    return instance
   }
 }

src/template/tag/tag.ts

@@ -28,7 +28,7 @@ export default class Tag extends Template<TagToken> implements ITemplate {
     }
   }
   async render (scope: Scope) {
-    const hash = new Hash(this.token.args, scope)
+    const hash = await Hash.create(this.token.args, scope)
     const impl = this.impl
     if (typeof impl.render !== 'function') {
       return ''

src/template/value.ts

@@ -47,10 +47,12 @@ export default class Value {
     }
     this.filters.push(new Filter(name, args, this.strictFilters))
   }
-  value (scope: Scope) {
-    return this.filters.reduce(
-      (prev, filter) => filter.render(prev, scope),
-      evalExp(this.initial, scope))
+  async value (scope: Scope) {
+    let val = await evalExp(this.initial, scope)
+    for (let filter of this.filters) {
+      val = await filter.render(val, scope)
+    }
+    return val
   }
   static tokenize (str: string): Array<'|' | ',' | ':' | string> {
     const tokens = []

test/e2e/eval-value.ts

@@ -5,7 +5,7 @@ describe('.evalValue()', function () {
   var engine: Liquid
   beforeEach(() => { engine = new Liquid() })
 
-  it('should throw when scope undefined', function () {
-    expect(() => engine.evalValue('{{"foo"}}', null as any)).to.throw(/scope undefined/)
+  it('should throw when scope undefined', async function () {
+    return expect(engine.evalValue('{{"foo"}}', null as any)).to.be.rejectedWith(/scope undefined/)
   })
 })

test/integration/builtin/filters/array.ts

@@ -33,9 +33,9 @@ describe('filters/array', function () {
                 ' | split: ", " %}{{ my_array | size }}',
       '4')
     })
-    it('should also be used with dot notation - string',
+    it('should be respected with <string>.size notation',
       () => test('{% assign my_string = "Ground control to Major Tom." %}{{ my_string.size }}', '28'))
-    it('should also be used with dot notation - array',
+    it('should be respected with <array>.size notation',
       () => test('{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}{{ my_array.size }}', '4'))
   })
   describe('slice', function () {

test/integration/builtin/tags/for.ts

@@ -1,7 +1,7 @@
 import Liquid from '../../../../src/liquid'
 import { expect, use } from 'chai'
 import * as chaiAsPromised from 'chai-as-promised'
-import { Context } from '../../../../src/scope/scope'
+import { Context } from '../../../../src/scope/context'
 
 use(chaiAsPromised)
 

test/integration/drop/drop.ts

@@ -8,17 +8,26 @@ describe('drop/drop', function () {
   class CustomDrop extends Liquid.Types.Drop {
     name: string = 'NAME'
     getName () {
-      return 'GETNAME'
+      return 'GET NAME'
     }
   }
   class CustomDropWithMethodMissing extends CustomDrop {
     liquidMethodMissing (key: string) {
       return key.toUpperCase()
     }
   }
+  class PromiseDrop extends Liquid.Types.Drop {
+    name = Promise.resolve('NAME')
+    async getName () {
+      return 'GET NAME'
+    }
+    async liquidMethodMissing (key: string) {
+      return key.toUpperCase()
+    }
+  }
   it('should call corresponding method', async function () {
     const html = await liquid.parseAndRender(`{{obj.getName}}`, { obj: new CustomDrop() })
-    expect(html).to.equal('GETNAME')
+    expect(html).to.equal('GET NAME')
   })
   it('should read corresponding property', async function () {
     const html = await liquid.parseAndRender(`{{obj.name}}`, { obj: new CustomDrop() })
@@ -32,4 +41,16 @@ describe('drop/drop', function () {
     const html = await liquid.parseAndRender(`{{obj.foo}}`, { obj: new CustomDropWithMethodMissing() })
     expect(html).to.equal('FOO')
   })
+  it('should call corresponding promise method', async function () {
+    const html = await liquid.parseAndRender(`{{obj.getName}}`, { obj: new PromiseDrop() })
+    expect(html).to.equal('GET NAME')
+  })
+  it('should read corresponding promise property', async function () {
+    const html = await liquid.parseAndRender(`{{obj.name}}`, { obj: new PromiseDrop() })
+    expect(html).to.equal('NAME')
+  })
+  it('should support promise returned by liquidMethodMissing', async function () {
+    const html = await liquid.parseAndRender(`{{obj.foo}}`, { obj: new PromiseDrop() })
+    expect(html).to.equal('FOO')
+  })
 })