feat: support filters in if/unless/case, see #287

src/builtin/tags/case.ts

@@ -1,16 +1,16 @@
-import { Expression, Emitter, TagToken, TopLevelToken, Context, Template, TagImplOptions, ParseStream } from '../../types'
+import { toValue, Value, Emitter, TagToken, TopLevelToken, Context, Template, TagImplOptions, ParseStream } from '../../types'
 
 export default {
   parse: function (tagToken: TagToken, remainTokens: TopLevelToken[]) {
-    this.cond = tagToken.args
+    this.cond = new Value(tagToken.args, this.liquid)
     this.cases = []
     this.elseTemplates = []
 
     let p: Template[] = []
     const stream: ParseStream = this.liquid.parser.parseStream(remainTokens)
       .on('tag:when', (token: TagToken) => {
         this.cases.push({
-          val: token.args,
+          val: new Value(token.args, this.liquid),
           templates: p = []
         })
       })
@@ -26,11 +26,9 @@ export default {
 
   render: function * (ctx: Context, emitter: Emitter) {
     const r = this.liquid.renderer
-    const { operators, operatorsTrie } = this.liquid.options
-    const cond = yield new Expression(this.cond, operators, operatorsTrie).value(ctx)
-    for (let i = 0; i < this.cases.length; i++) {
-      const branch = this.cases[i]
-      const val = yield new Expression(branch.val, operators, operatorsTrie).value(ctx)
+    const cond = toValue(yield this.cond.value(ctx, ctx.opts.lenientIf))
+    for (const branch of this.cases) {
+      const val = toValue(yield branch.val.value(ctx, ctx.opts.lenientIf))
       if (val === cond) {
         yield r.renderTemplates(branch.templates, ctx, emitter)
         return

src/builtin/tags/if.ts

@@ -1,4 +1,4 @@
-import { Emitter, isTruthy, Expression, TagToken, TopLevelToken, Context, Template, TagImplOptions, ParseStream } from '../../types'
+import { Value, Emitter, isTruthy, TagToken, TopLevelToken, Context, Template, TagImplOptions, ParseStream } from '../../types'
 
 export default {
   parse: function (tagToken: TagToken, remainTokens: TopLevelToken[]) {
@@ -8,12 +8,12 @@ export default {
     let p
     const stream: ParseStream = this.liquid.parser.parseStream(remainTokens)
       .on('start', () => this.branches.push({
-        cond: tagToken.args,
+        cond: new Value(tagToken.args, this.liquid),
         templates: (p = [])
       }))
       .on('tag:elsif', (token: TagToken) => {
         this.branches.push({
-          cond: token.args,
+          cond: new Value(token.args, this.liquid),
           templates: p = []
         })
       })
@@ -29,10 +29,9 @@ export default {
 
   render: function * (ctx: Context, emitter: Emitter) {
     const r = this.liquid.renderer
-    const { operators, operatorsTrie } = this.liquid.options
 
     for (const branch of this.branches) {
-      const cond = yield new Expression(branch.cond, operators, operatorsTrie, ctx.opts.lenientIf).value(ctx)
+      const cond = yield branch.cond.value(ctx, ctx.opts.lenientIf)
       if (isTruthy(cond, ctx)) {
         yield r.renderTemplates(branch.templates, ctx, emitter)
         return

src/builtin/tags/unless.ts

@@ -1,4 +1,4 @@
-import { TopLevelToken, Template, Emitter, Expression, isTruthy, isFalsy, ParseStream, Context, TagImplOptions, TagToken } from '../../types'
+import { Value, TopLevelToken, Template, Emitter, isTruthy, isFalsy, ParseStream, Context, TagImplOptions, TagToken } from '../../types'
 
 export default {
   parse: function (tagToken: TagToken, remainTokens: TopLevelToken[]) {
@@ -9,11 +9,11 @@ export default {
     const stream: ParseStream = this.liquid.parser.parseStream(remainTokens)
       .on('start', () => {
         p = this.templates
-        this.cond = tagToken.args
+        this.cond = new Value(tagToken.args, this.liquid)
       })
       .on('tag:elsif', (token: TagToken) => {
         this.branches.push({
-          cond: token.args,
+          cond: new Value(token.args, this.liquid),
           templates: p = []
         })
       })
@@ -29,16 +29,15 @@ export default {
 
   render: function * (ctx: Context, emitter: Emitter) {
     const r = this.liquid.renderer
-    const { operators, operatorsTrie } = this.liquid.options
-    const cond = yield new Expression(this.cond, operators, operatorsTrie, ctx.opts.lenientIf).value(ctx)
+    const cond = yield this.cond.value(ctx, ctx.opts.lenientIf)
 
     if (isFalsy(cond, ctx)) {
       yield r.renderTemplates(this.templates, ctx, emitter)
       return
     }
 
     for (const branch of this.branches) {
-      const cond = yield new Expression(branch.cond, operators, operatorsTrie, ctx.opts.lenientIf).value(ctx)
+      const cond = yield branch.cond.value(ctx, ctx.opts.lenientIf)
       if (isTruthy(cond, ctx)) {
         yield r.renderTemplates(branch.templates, ctx, emitter)
         return

src/liquid.ts

@@ -101,8 +101,8 @@ export class Liquid {
   }
 
   public _evalValue (str: string, ctx: Context): IterableIterator<any> {
-    const value = new Value(str, this.filters, this)
-    return value.value(ctx)
+    const value = new Value(str, this)
+    return value.value(ctx, false)
   }
   public async evalValue (str: string, ctx: Context): Promise<any> {
     return toPromise(this._evalValue(str, ctx))

src/parser/parser.ts

@@ -29,7 +29,7 @@ export default class Parser {
         return new Tag(token, remainTokens, this.liquid)
       }
       if (isOutputToken(token)) {
-        return new Output(token as OutputToken, this.liquid.filters, this.liquid)
+        return new Output(token as OutputToken, this.liquid)
       }
       return new HTML(token)
     } catch (e) {

src/parser/tokenizer.ts

@@ -23,6 +23,7 @@ import { NormalizedFullOptions, defaultOptions } from '../liquid-options'
 import { TYPES, QUOTE, BLANK, IDENTIFIER } from '../util/character'
 import { matchOperator } from './match-operator'
 import { Trie } from '../util/operator-trie'
+import { Expression } from '../render/expression'
 
 export class Tokenizer {
   p = 0
@@ -37,7 +38,11 @@ export class Tokenizer {
     this.N = input.length
   }
 
-  * readExpression (): IterableIterator<Token> {
+  readExpression () {
+    return new Expression(this.readExpressionTokens())
+  }
+
+  * readExpressionTokens (): IterableIterator<Token> {
     const operand = this.readValue()
     if (!operand) return
 

src/render/expression.ts

@@ -1,4 +1,5 @@
 import { QuotedToken } from '../tokens/quoted-token'
+import { PropertyAccessToken } from '../tokens/property-access-token'
 import { NumberToken } from '../tokens/number-token'
 import { assert } from '../util/assert'
 import { literalValues } from '../util/literal'
@@ -9,64 +10,53 @@ import { OperatorToken } from '../tokens/operator-token'
 import { RangeToken } from '../tokens/range-token'
 import { parseStringLiteral } from '../parser/parse-string-literal'
 import { Context } from '../context/context'
-import { range, toValue } from '../util/underscore'
-import { Tokenizer } from '../parser/tokenizer'
+import { range } from '../util/underscore'
 import { Operators } from '../render/operator'
 import { UndefinedVariableError, InternalUndefinedVariableError } from '../util/error'
-import { Trie } from '../util/operator-trie'
 
 export class Expression {
-  private operands: any[] = []
   private postfix: Token[]
-  private lenient: boolean
-  private operators: Operators
 
-  public constructor (str: string, operators: Operators, operatorsTrie: Trie, lenient = false) {
-    const tokenizer = new Tokenizer(str, operatorsTrie)
-    this.postfix = [...toPostfix(tokenizer.readExpression())]
-    this.lenient = lenient
-    this.operators = operators
+  public constructor (tokens: IterableIterator<Token>) {
+    this.postfix = [...toPostfix(tokens)]
   }
-  public evaluate (ctx: Context): any {
+  public * evaluate (ctx: Context, lenient: boolean): any {
+    assert(ctx, () => 'unable to evaluate: context not defined')
+    const operands: any[] = []
     for (const token of this.postfix) {
       if (TypeGuards.isOperatorToken(token)) {
-        const r = this.operands.pop()
-        const l = this.operands.pop()
-        const result = evalOperatorToken(this.operators, token, l, r, ctx)
-        this.operands.push(result)
+        const r = yield operands.pop()
+        const l = yield operands.pop()
+        const result = evalOperatorToken(ctx.opts.operators, token, l, r, ctx)
+        operands.push(result)
       } else {
-        this.operands.push(evalToken(token, ctx, this.lenient && this.postfix.length === 1))
+        operands.push(yield evalToken(token, ctx, lenient && this.postfix.length === 1))
       }
     }
-    return this.operands[0]
-  }
-  public * value (ctx: Context) {
-    return toValue(this.evaluate(ctx))
+    return operands[0]
   }
 }
 
 export function evalToken (token: Token | undefined, ctx: Context, lenient = false): any {
-  assert(ctx, () => 'unable to evaluate: context not defined')
-  if (TypeGuards.isPropertyAccessToken(token)) {
-    const variable = token.getVariableAsText()
-    const props: string[] = token.props.map(prop => evalToken(prop, ctx))
-    try {
-      return ctx.get([variable, ...props])
-    } catch (e) {
-      if (lenient && e instanceof InternalUndefinedVariableError) {
-        return null
-      } else {
-        throw (new UndefinedVariableError(e, token))
-      }
-    }
-  }
+  if (TypeGuards.isPropertyAccessToken(token)) return evalPropertyAccessToken(token, ctx, lenient)
   if (TypeGuards.isRangeToken(token)) return evalRangeToken(token, ctx)
   if (TypeGuards.isLiteralToken(token)) return evalLiteralToken(token)
   if (TypeGuards.isNumberToken(token)) return evalNumberToken(token)
   if (TypeGuards.isWordToken(token)) return token.getText()
   if (TypeGuards.isQuotedToken(token)) return evalQuotedToken(token)
 }
 
+function evalPropertyAccessToken (token: PropertyAccessToken, ctx: Context, lenient: boolean) {
+  const variable = token.getVariableAsText()
+  const props: string[] = token.props.map(prop => evalToken(prop, ctx, false))
+  try {
+    return ctx.get([variable, ...props])
+  } catch (e) {
+    if (lenient && e instanceof InternalUndefinedVariableError) return null
+    throw (new UndefinedVariableError(e, token))
+  }
+}
+
 function evalNumberToken (token: NumberToken) {
   const str = token.whole.content + '.' + (token.decimal ? token.decimal.content : '')
   return Number(str)

src/template/filter/filter.ts

@@ -17,12 +17,12 @@ export class Filter {
     this.args = args
     this.liquid = liquid
   }
-  public * render (value: any, context: Context) {
+  public render (value: any, context: Context) {
     const argv: any[] = []
     for (const arg of this.args as FilterArg[]) {
-      if (isKeyValuePair(arg)) argv.push([arg[0], yield evalToken(arg[1], context)])
-      else argv.push(yield evalToken(arg, context))
+      if (isKeyValuePair(arg)) argv.push([arg[0], evalToken(arg[1], context)])
+      else argv.push(evalToken(arg, context))
     }
-    return yield this.impl.apply({ context, liquid: this.liquid }, [value, ...argv])
+    return this.impl.apply({ context, liquid: this.liquid }, [value, ...argv])
   }
 }

src/template/output.ts

@@ -1,5 +1,4 @@
 import { Value } from './value'
-import { FilterMap } from './filter/filter-map'
 import { TemplateImpl } from '../template/template-impl'
 import { Template } from '../template/template'
 import { Context } from '../context/context'
@@ -9,12 +8,12 @@ import { Liquid } from '../liquid'
 
 export class Output extends TemplateImpl<OutputToken> implements Template {
   private value: Value
-  public constructor (token: OutputToken, filters: FilterMap, liquid: Liquid) {
+  public constructor (token: OutputToken, liquid: Liquid) {
     super(token)
-    this.value = new Value(token.content, filters, liquid)
+    this.value = new Value(token.content, liquid)
   }
   public * render (ctx: Context, emitter: Emitter) {
-    const val = yield this.value.value(ctx)
+    const val = yield this.value.value(ctx, false)
     emitter.write(val)
   }
 }

src/template/value.ts

@@ -1,27 +1,25 @@
-import { evalToken } from '../render/expression'
+import { Expression } from '../render/expression'
 import { Tokenizer } from '../parser/tokenizer'
-import { FilterMap } from '../template/filter/filter-map'
 import { Filter } from './filter/filter'
 import { Context } from '../context/context'
-import { ValueToken } from '../tokens/value-token'
 import { Liquid } from '../liquid'
 
 export class Value {
   public readonly filters: Filter[] = []
-  public readonly initial?: ValueToken
+  public readonly initial: Expression
 
   /**
    * @param str the value to be valuated, eg.: "foobar" | truncate: 3
    */
-  public constructor (str: string, private readonly filterMap: FilterMap, liquid: Liquid) {
+  public constructor (str: string, liquid: Liquid) {
     const tokenizer = new Tokenizer(str, liquid.options.operatorsTrie)
-    this.initial = tokenizer.readValue()
-    this.filters = tokenizer.readFilters().map(({ name, args }) => new Filter(name, this.filterMap.get(name), args, liquid))
+    this.initial = tokenizer.readExpression()
+    this.filters = tokenizer.readFilters().map(({ name, args }) => new Filter(name, liquid.filters.get(name), args, liquid))
   }
-  public * value (ctx: Context) {
-    const lenient = ctx.opts.lenientIf && this.filters.length > 0 && this.filters[0].name === 'default'
+  public * value (ctx: Context, lenient: boolean) {
+    lenient = lenient || (ctx.opts.lenientIf && this.filters.length > 0 && this.filters[0].name === 'default')
+    let val = yield this.initial.evaluate(ctx, lenient)
 
-    let val = yield evalToken(this.initial, ctx, lenient)
     for (const filter of this.filters) {
       val = yield filter.render(val, ctx)
     }

src/types.ts

@@ -17,6 +17,9 @@ export { Token } from './tokens/token'
 export { TopLevelToken } from './tokens/toplevel-token'
 export { Tokenizer } from './parser/tokenizer'
 export { Hash } from './template/tag/hash'
+export { Value } from './template/value'
 export { evalToken, evalQuotedToken } from './render/expression'
-export { toPromise, toThenable, toValue } from './util/async'
+export { toPromise, toThenable } from './util/async'
 export { defaultOperators, Operators } from './render/operator'
+export { createTrie, Trie } from './util/operator-trie'
+export { toValue } from './util/underscore'

test/integration/builtin/tags/assign.ts

@@ -76,9 +76,9 @@ describe('tags/assign', function () {
       return expect(html).to.equal('11')
     })
     it('should write to the root scope', async function () {
-      const src = '{%for a in (1..2)%}{%assign num = a%}{{a}}{%endfor%} {{num}}'
+      const src = '{%for a in (1..2)%}{%assign num = a%}{{a}}{%endfor%}'
       const html = await liquid.parseAndRender(src, { num: 1 })
-      return expect(html).to.equal('12 2')
+      return expect(html).to.equal('12')
     })
     it('should not change input scope', async function () {
       const src = '{%for a in (1..2)%}{%assign num = a%}{{a}}{%endfor%} {{num}}'

test/integration/builtin/tags/if.ts

@@ -80,6 +80,14 @@ describe('tags/if', function () {
       return expect(html).to.equal('success')
     })
   })
+  describe('filters as condition', function () {
+    it('should support filter on expression', async function () {
+      liquid.registerFilter('negate', (val) => !val)
+      const src = '{% if 2 == 3 | negate %}yes{%else%}no{%endif%}'
+      const html = await liquid.parseAndRender(src, scope)
+      return expect(html).to.equal('yes')
+    })
+  })
   describe('compare to null', function () {
     it('should evaluate false for null < 10', async function () {
       const src = '{% if null < 10 %}yes{% else %}no{% endif %}'

test/integration/liquid/strict.ts

@@ -1,5 +1,9 @@
 import { Liquid } from '../../../src/liquid'
-import { expect } from 'chai'
+import * as chai from 'chai'
+import * as chaiAsPromised from 'chai-as-promised'
+
+chai.use(chaiAsPromised)
+const expect = chai.expect
 
 describe('LiquidOptions#strict*', function () {
   let engine: Liquid
@@ -60,5 +64,9 @@ describe('LiquidOptions#strict*', function () {
       const html = await engine.render(tpl, ctx, strictLenientOpts)
       return expect(html).to.equal('a')
     })
+    it('should not allow undefined variable even if `lenientIf` set', async function () {
+      const tpl = engine.parse('{{notdefined | tolower}}')
+      return expect(() => engine.renderSync(tpl, ctx, strictLenientOpts)).to.throw('undefined variable: notdefined')
+    })
   })
 })