feat: allow drops in property access (#769)

Author: santialbo

src/context/context.ts

@@ -3,7 +3,7 @@ import { Drop } from '../drop/drop'
 import { __assign } from 'tslib'
 import { NormalizedFullOptions, defaultOptions, RenderOptions } from '../liquid-options'
 import { Scope } from './scope'
-import { hasOwnProperty, isArray, isNil, isUndefined, isString, isFunction, toLiquid, InternalUndefinedVariableError, toValueSync, isObject, Limiter } from '../util'
+import { hasOwnProperty, isArray, isNil, isUndefined, isString, isFunction, toLiquid, InternalUndefinedVariableError, toValueSync, isObject, Limiter, toValue } from '../util'
 
 type PropertyKey = string | number;
 
@@ -71,8 +71,8 @@ export class Context {
   public getSync (paths: PropertyKey[]): unknown {
     return toValueSync(this._get(paths))
   }
-  public * _get (paths: PropertyKey[]): IterableIterator<unknown> {
-    const scope = this.findScope(paths[0])
+  public * _get (paths: (PropertyKey | Drop)[]): IterableIterator<unknown> {
+    const scope = this.findScope(paths[0] as string) // first prop should always be a string
     return yield this._getFromScope(scope, paths)
   }
   /**
@@ -81,7 +81,7 @@ export class Context {
   public getFromScope (scope: unknown, paths: PropertyKey[] | string): IterableIterator<unknown> {
     return toValueSync(this._getFromScope(scope, paths))
   }
-  public * _getFromScope (scope: unknown, paths: PropertyKey[] | string, strictVariables = this.strictVariables): IterableIterator<unknown> {
+  public * _getFromScope (scope: unknown, paths: (PropertyKey | Drop)[] | string, strictVariables = this.strictVariables): IterableIterator<unknown> {
     if (isString(paths)) paths = paths.split('.')
     for (let i = 0; i < paths.length; i++) {
       scope = yield readProperty(scope as object, paths[i], this.ownPropertyOnly)
@@ -120,8 +120,9 @@ export class Context {
   }
 }
 
-export function readProperty (obj: Scope, key: PropertyKey, ownPropertyOnly: boolean) {
+export function readProperty (obj: Scope, key: (PropertyKey | Drop), ownPropertyOnly: boolean) {
   obj = toLiquid(obj)
+  key = toValue(key) as PropertyKey
   if (isNil(obj)) return obj
   if (isArray(obj) && (key as number) < 0) return obj[obj.length + +key]
   const value = readJSProperty(obj, key, ownPropertyOnly)

src/render/expression.spec.ts

@@ -50,6 +50,16 @@ describe('Expression', function () {
       expect(await toPromise(create('foo[doo["foo"]]').evaluate(ctx, false))).toBe('BAR')
       expect(await toPromise(create('doo[coo].foo').evaluate(ctx, false))).toBe('bar')
     })
+    it('should support drops in property access', async function () {
+      class TemplateDrop extends Drop {
+        valueOf () { return 'bar' }
+      }
+      const ctx = new Context({
+        foo: { bar: 'BAR' },
+        coo: new TemplateDrop()
+      })
+      expect(await toPromise(create('foo[coo]').evaluate(ctx, false))).toBe('BAR')
+    })
   })
 
   describe('simple expression', function () {

src/render/expression.ts

@@ -2,6 +2,7 @@ import { QuotedToken, RangeToken, OperatorToken, Token, PropertyAccessToken, Ope
 import { isRangeToken, isPropertyAccessToken, UndefinedVariableError, range, isOperatorToken, assert } from '../util'
 import type { Context } from '../context'
 import type { UnaryOperatorHandler } from '../render'
+import { Drop } from '../drop'
 
 export class Expression {
   private postfix: Token[]
@@ -42,9 +43,9 @@ export function * evalToken (token: Token | undefined, ctx: Context, lenient = f
 }
 
 function * evalPropertyAccessToken (token: PropertyAccessToken, ctx: Context, lenient: boolean): IterableIterator<unknown> {
-  const props: string[] = []
+  const props: (string | number | Drop)[] = []
   for (const prop of token.props) {
-    props.push((yield evalToken(prop, ctx, false)) as unknown as string)
+    props.push((yield evalToken(prop, ctx, false)) as unknown as string | number | Drop)
   }
   try {
     if (token.variable) {