refactor: rewrite expression evaluation, fix #130

src/builtin/filters/array.ts

@@ -1,5 +1,5 @@
 import { isArray, last } from '../../util/underscore'
-import { isTruthy } from '../../render/syntax'
+import { isTruthy } from '../../render/boolean'
 
 export default {
   'join': (v: any[], arg: string) => v.join(arg === undefined ? ' ' : arg),

src/builtin/filters/object.ts

@@ -1,4 +1,4 @@
-import { isFalsy } from '../../render/syntax'
+import { isFalsy } from '../../render/boolean'
 import { toValue } from '../../util/underscore'
 
 export default {

src/builtin/tags/assign.ts

@@ -1,8 +1,6 @@
 import { assert } from '../../util/assert'
 import { identifier } from '../../parser/lexical'
-import { TagToken } from '../../parser/tag-token'
-import { Context } from '../../context/context'
-import { ITagImplOptions } from '../../template/tag/itag-impl-options'
+import { ITagImplOptions, TagToken, Context } from '../../types'
 
 const re = new RegExp(`(${identifier.source})\\s*=([^]*)`)
 

src/builtin/tags/case.ts

@@ -1,5 +1,4 @@
-import { Hash, Emitter, TagToken, Token, Context, ITemplate, ITagImplOptions, ParseStream } from '../../types'
-import { evalExp } from '../../render/syntax'
+import { Expression, Hash, Emitter, TagToken, Token, Context, ITemplate, ITagImplOptions, ParseStream } from '../../types'
 
 export default {
   parse: function (tagToken: TagToken, remainTokens: Token[]) {
@@ -28,8 +27,8 @@ export default {
   render: async function (ctx: Context, hash: Hash, emitter: Emitter) {
     for (let i = 0; i < this.cases.length; i++) {
       const branch = this.cases[i]
-      const val = await evalExp(branch.val, ctx)
-      const cond = await evalExp(this.cond, ctx)
+      const val = new Expression(branch.val).value(ctx)
+      const cond = new Expression(this.cond).value(ctx)
       if (val === cond) {
         this.liquid.renderer.renderTemplates(branch.templates, ctx, emitter)
         return

src/builtin/tags/cycle.ts

@@ -1,6 +1,6 @@
 import { assert } from '../../util/assert'
 import { value as rValue } from '../../parser/lexical'
-import { evalValue } from '../../render/syntax'
+import { Expression } from '../../render/expression'
 import { TagToken } from '../../parser/tag-token'
 import { Context } from '../../context/context'
 import { ITagImplOptions } from '../../template/tag/itag-impl-options'
@@ -13,7 +13,7 @@ export default {
     let match: RegExpExecArray | null = groupRE.exec(tagToken.args) as RegExpExecArray
     assert(match, `illegal tag: ${tagToken.raw}`)
 
-    this.group = match[1] || ''
+    this.group = new Expression(match[1])
     const candidates = match[2]
 
     this.candidates = []
@@ -25,7 +25,7 @@ export default {
   },
 
   render: async function (ctx: Context) {
-    const group = await evalValue(this.group, ctx)
+    const group = this.group.value(ctx)
     const fingerprint = `cycle:${group}:` + this.candidates.join(',')
     const groups = ctx.getRegister('cycle')
     let idx = groups[fingerprint]
@@ -38,6 +38,6 @@ export default {
     idx = (idx + 1) % this.candidates.length
     groups[fingerprint] = idx
 
-    return evalValue(candidate, ctx)
+    return new Expression(candidate).value(ctx)
   }
 } as ITagImplOptions

src/builtin/tags/for.ts

@@ -1,6 +1,6 @@
 import { Emitter, TagToken, Token, Context, ITemplate, ITagImplOptions, ParseStream } from '../../types'
 import { isString, isObject, isArray } from '../../util/underscore'
-import { parseExp } from '../../render/syntax'
+import { Expression } from '../../render/expression'
 import { assert } from '../../util/assert'
 import { identifier, value, hash } from '../../parser/lexical'
 import { ForloopDrop } from '../../drop/forloop-drop'
@@ -37,7 +37,7 @@ export default {
     stream.start()
   },
   render: async function (ctx: Context, hash: Hash, emitter: Emitter) {
-    let collection = await parseExp(this.collection, ctx)
+    let collection = new Expression(this.collection).value(ctx)
 
     if (!isArray(collection)) {
       if (isString(collection) && collection.length > 0) {

src/builtin/tags/if.ts

@@ -1,4 +1,4 @@
-import { Hash, Emitter, evalExp, isTruthy, TagToken, Token, Context, ITemplate, ITagImplOptions, ParseStream } from '../../types'
+import { Hash, Emitter, isTruthy, Expression, TagToken, Token, Context, ITemplate, ITagImplOptions, ParseStream } from '../../types'
 
 export default {
   parse: function (tagToken: TagToken, remainTokens: Token[]) {
@@ -29,7 +29,7 @@ export default {
 
   render: async function (ctx: Context, hash: Hash, emitter: Emitter) {
     for (const branch of this.branches) {
-      const cond = await evalExp(branch.cond, ctx)
+      const cond = new Expression(branch.cond).value(ctx)
       if (isTruthy(cond)) {
         await this.liquid.renderer.renderTemplates(branch.templates, ctx, emitter)
         return

src/builtin/tags/include.ts

@@ -1,7 +1,6 @@
 import { assert } from '../../util/assert'
-import { Hash, Emitter, TagToken, Context, ITagImplOptions } from '../../types'
+import { Expression, Hash, Emitter, TagToken, Context, ITagImplOptions } from '../../types'
 import { value, quotedLine } from '../../parser/lexical'
-import { evalValue, parseValue } from '../../render/syntax'
 import BlockMode from '../../context/block-mode'
 
 const staticFileRE = /[^\s,]+/
@@ -25,7 +24,7 @@ export default {
         const template = this.value.slice(1, -1)
         filepath = await this.liquid.parseAndRender(template, ctx.getAll(), ctx.opts)
       } else {
-        filepath = await evalValue(this.value, ctx)
+        filepath = new Expression(this.value).value(ctx)
       }
     } else {
       filepath = this.staticValue
@@ -38,7 +37,7 @@ export default {
     ctx.setRegister('blocks', {})
     ctx.setRegister('blockMode', BlockMode.OUTPUT)
     if (this.with) {
-      hash[filepath] = await parseValue(this.with, ctx)
+      hash[filepath] = new Expression(this.with).evaluate(ctx)
     }
     const templates = await this.liquid.getTemplate(filepath, ctx.opts)
     ctx.push(hash)

src/builtin/tags/layout.ts

@@ -1,7 +1,6 @@
 import { assert } from '../../util/assert'
 import { value as rValue } from '../../parser/lexical'
-import { evalValue } from '../../render/syntax'
-import { TagToken, Token, Context, ITagImplOptions } from '../../types'
+import { Expression, TagToken, Token, Context, ITagImplOptions } from '../../types'
 import BlockMode from '../../context/block-mode'
 import { Hash } from '../../template/tag/hash'
 
@@ -23,7 +22,7 @@ export default {
   },
   render: async function (ctx: Context, hash: Hash) {
     const layout = ctx.opts.dynamicPartials
-      ? await evalValue(this.layout, ctx)
+      ? await (new Expression(this.layout).value(ctx))
       : this.staticLayout
     assert(layout, `cannot apply layout with empty filename`)
 

src/builtin/tags/tablerow.ts

@@ -1,5 +1,5 @@
 import { assert } from '../../util/assert'
-import { evalExp, Emitter, Hash, TagToken, Token, Context, ITemplate, ITagImplOptions, ParseStream } from '../../types'
+import { Expression, Emitter, Hash, TagToken, Token, Context, ITemplate, ITagImplOptions, ParseStream } from '../../types'
 import { identifier, value, hash } from '../../parser/lexical'
 import { TablerowloopDrop } from '../../drop/tablerowloop-drop'
 
@@ -29,7 +29,7 @@ export default {
   },
 
   render: async function (ctx: Context, hash: Hash, emitter: Emitter) {
-    let collection = await evalExp(this.collection, ctx) || []
+    let collection = new Expression(this.collection).value(ctx) || []
     const offset = hash.offset || 0
     const limit = (hash.limit === undefined) ? collection.length : hash.limit
 

src/builtin/tags/unless.ts

@@ -1,4 +1,4 @@
-import { Emitter, evalExp, isFalsy, ParseStream, Context, ITagImplOptions, Token, Hash, TagToken } from '../../types'
+import { Emitter, Expression, isFalsy, ParseStream, Context, ITagImplOptions, Token, Hash, TagToken } from '../../types'
 
 export default {
   parse: function (tagToken: TagToken, remainTokens: Token[]) {
@@ -21,7 +21,7 @@ export default {
   },
 
   render: async function (ctx: Context, hash: Hash, emitter: Emitter) {
-    const cond = await evalExp(this.cond, ctx)
+    const cond = new Expression(this.cond).value(ctx)
     isFalsy(cond)
       ? await this.liquid.renderer.renderTemplates(this.templates, ctx, emitter)
       : await this.liquid.renderer.renderTemplates(this.elseTemplates, ctx, emitter)

src/parser/literal.ts

@@ -0,0 +1,18 @@
+import { last } from '../util/underscore'
+import { NullDrop } from '../drop/null-drop'
+import { EmptyDrop } from '../drop/empty-drop'
+import { BlankDrop } from '../drop/blank-drop'
+
+type literal = true | false | NullDrop | EmptyDrop | BlankDrop | number | string
+
+export function parseLiteral (str: string): literal | undefined {
+  str = str.trim()
+
+  if (str === 'true') return true
+  if (str === 'false') return false
+  if (str === 'nil' || str === 'null') return new NullDrop()
+  if (str === 'empty') return new EmptyDrop()
+  if (str === 'blank') return new BlankDrop()
+  if (!isNaN(Number(str))) return Number(str)
+  if ((str[0] === '"' || str[0] === "'") && str[0] === last(str)) return str.slice(1, -1)
+}

src/render/boolean.ts

@@ -0,0 +1,6 @@
+export function isTruthy (val: any): boolean {
+  return !isFalsy(val)
+}
+export function isFalsy (val: any): boolean {
+  return val === false || undefined === val || val === null
+}

src/render/expression.ts

@@ -0,0 +1,82 @@
+import { assert } from '../util/assert'
+import { isRange, rangeValue } from './range'
+import { Value } from './value'
+import { Context } from '../context/context'
+import { toValue } from '../util/underscore'
+import { isOperator, precedence, operatorImpls } from './operator'
+
+export class Expression {
+  private str: string
+
+  public constructor (str: string = '') {
+    this.str = str
+  }
+  public evaluate (ctx: Context): any {
+    assert(ctx, 'unable to evaluate: context not defined')
+
+    const operands = []
+    for (const token of toPostfix(this.str)) {
+      if (isOperator(token)) {
+        const r = operands.pop()
+        const l = operands.pop()
+        const result = operatorImpls[token](l, r)
+        operands.push(result)
+        continue
+      }
+      if (isRange(token)) {
+        operands.push(rangeValue(token, ctx))
+        continue
+      }
+      operands.push(new Value(token).evaluate(ctx))
+    }
+    return operands[0]
+  }
+  public value (ctx: Context): any {
+    return toValue(this.evaluate(ctx))
+  }
+}
+
+function * tokenize (expr: string): IterableIterator<string> {
+  const N = expr.length
+  let str = ''
+  const pairs = { '"': '"', "'": "'", '[': ']', '(': ')' }
+
+  for (let i = 0; i < N; i++) {
+    const c = expr[i]
+    switch (c) {
+      case '[':
+      case '"':
+      case "'":
+        str += c
+        while (i + 1 < N) {
+          str += expr[++i]
+          if (expr[i] === pairs[c]) break
+        }
+        break
+      case ' ':
+      case '\t':
+      case '\n':
+        if (str) yield str
+        str = ''
+        break
+      default:
+        str += c
+    }
+  }
+  if (str) yield str
+}
+
+function * toPostfix (expr: string): IterableIterator<string> {
+  const ops = []
+  for (const token of tokenize(expr)) {
+    if (isOperator(token)) {
+      while (ops.length && precedence[ops[ops.length - 1]] > precedence[token]) {
+        yield ops.pop()!
+      }
+      ops.push(token)
+    } else yield token
+  }
+  while (ops.length) {
+    yield ops.pop()!
+  }
+}

src/render/operator.ts

@@ -0,0 +1,59 @@
+import { isComparable } from '../drop/icomparable'
+import { isFunction } from '../util/underscore'
+import { isTruthy } from '../render/boolean'
+
+export const precedence = {
+  '==': 1,
+  '!=': 1,
+  '>': 1,
+  '<': 1,
+  '>=': 1,
+  '<=': 1,
+  'contains': 1,
+  'and': 0,
+  'or': 0
+}
+
+export const operatorImpls: {[key: string]: (lhs: any, rhs: any) => boolean} = {
+  '==': (l: any, r: any) => {
+    if (isComparable(l)) return l.equals(r)
+    if (isComparable(r)) return r.equals(l)
+    return l === r
+  },
+  '!=': (l: any, r: any) => {
+    if (isComparable(l)) return !l.equals(r)
+    if (isComparable(r)) return !r.equals(l)
+    return l !== r
+  },
+  '>': (l: any, r: any) => {
+    if (isComparable(l)) return l.gt(r)
+    if (isComparable(r)) return r.lt(l)
+    return l > r
+  },
+  '<': (l: any, r: any) => {
+    if (isComparable(l)) return l.lt(r)
+    if (isComparable(r)) return r.gt(l)
+    return l < r
+  },
+  '>=': (l: any, r: any) => {
+    if (isComparable(l)) return l.geq(r)
+    if (isComparable(r)) return r.leq(l)
+    return l >= r
+  },
+  '<=': (l: any, r: any) => {
+    if (isComparable(l)) return l.leq(r)
+    if (isComparable(r)) return r.geq(l)
+    return l <= r
+  },
+  'contains': (l: any, r: any) => {
+    return l && isFunction(l.indexOf) ? l.indexOf(r) > -1 : false
+  },
+  'and': (l: any, r: any) => isTruthy(l) && isTruthy(r),
+  'or': (l: any, r: any) => isTruthy(l) || isTruthy(r)
+}
+
+const list = Object.keys(precedence)
+
+export function isOperator (token: string) {
+  return list.includes(token)
+}

src/render/range.ts

@@ -0,0 +1,17 @@
+import { rangeLine } from '../parser/lexical'
+import { Context } from '../context/context'
+import { range } from '../util/underscore'
+import { Value } from './value'
+
+export function isRange (token: string = '') {
+  return token[0] === '(' && token[token.length - 1] === ')'
+}
+
+export function rangeValue (token: string = '', ctx: Context) {
+  let match
+  if ((match = token.match(rangeLine))) {
+    const low = new Value(match[1]).value(ctx)
+    const high = new Value(match[2]).value(ctx)
+    return range(+low, +high + 1)
+  }
+}