Fixup JSON AST conversion

lib/fromJSON.js

@@ -8,35 +8,40 @@ let Input = require('./input')
 let Root = require('./root')
 let Rule = require('./rule')
 
-function fromJSON (json) {
-  let defaults = { ...json }
-  if (json.nodes) {
-    defaults.nodes = json.nodes.map(i => fromJSON(i))
-  }
-  if (json.type === 'root') {
-    if (defaults.source) {
-      defaults.source = { ...defaults.source }
-      if (defaults.source.input) {
-        defaults.source.input = {
-          ...defaults.source.input,
-          __proto__: Input.prototype
-        }
-        if (defaults.source.input.map) {
-          defaults.source.input.map = {
-            ...defaults.source.input.map,
-            __proto__: PreviousMap.prototype
-          }
+function fromJSON (json, inputs) {
+  let { inputs: ownInputs, ...defaults } = json
+  if (ownInputs) {
+    inputs = []
+    for (let input of ownInputs) {
+      let inputHydrated = { ...input, __proto__: Input.prototype }
+      if (inputHydrated.map) {
+        inputHydrated.map = {
+          ...inputHydrated.map,
+          __proto__: PreviousMap.prototype
         }
       }
+      inputs.push(inputHydrated)
+    }
+  }
+  if (defaults.nodes) {
+    defaults.nodes = json.nodes.map(n => fromJSON(n, inputs))
+  }
+  if (defaults.source) {
+    let { inputId, ...source } = defaults.source
+    defaults.source = source
+    if (inputId != null) {
+      defaults.source.input = inputs[inputId]
     }
+  }
+  if (defaults.type === 'root') {
     return new Root(defaults)
-  } else if (json.type === 'decl') {
+  } else if (defaults.type === 'decl') {
     return new Declaration(defaults)
-  } else if (json.type === 'rule') {
+  } else if (defaults.type === 'rule') {
     return new Rule(defaults)
-  } else if (json.type === 'comment') {
+  } else if (defaults.type === 'comment') {
     return new Comment(defaults)
-  } else if (json.type === 'atrule') {
+  } else if (defaults.type === 'atrule') {
     return new AtRule(defaults)
   } else {
     throw new Error('Unknown node type: ' + json.type)

lib/node.js

@@ -166,8 +166,11 @@ class Node {
     if (!keepBetween) delete this.raws.between
   }
 
-  toJSON () {
+  toJSON (inputs) {
     let fixed = {}
+    let emitInputs = inputs == null
+    inputs = inputs || new Map()
+    let inputsNextIndex = 0
 
     for (let name in this) {
       if (!Object.prototype.hasOwnProperty.call(this, name)) {
@@ -180,23 +183,34 @@ class Node {
       if (Array.isArray(value)) {
         fixed[name] = value.map(i => {
           if (typeof i === 'object' && i.toJSON) {
-            return i.toJSON()
+            return i.toJSON(inputs)
           } else {
             return i
           }
         })
       } else if (typeof value === 'object' && value.toJSON) {
-        fixed[name] = value.toJSON()
-      } else if (this.type === 'root' && name === 'source') {
+        fixed[name] = value.toJSON(inputs)
+      } else if (name === 'source') {
+        let inputId = inputs.get(value.input)
+        if (inputId == null) {
+          inputId = inputsNextIndex
+          inputs.set(value.input, inputsNextIndex)
+          inputsNextIndex++
+        }
         fixed[name] = {
-          input: value.input.toJSON(),
-          start: value.start
+          inputId,
+          start: value.start,
+          end: value.end
         }
       } else {
         fixed[name] = value
       }
     }
 
+    if (emitInputs) {
+      fixed.inputs = [...inputs.keys()].map(input => input.toJSON())
+    }
+
     return fixed
   }
 

test/fromJSON.test.ts

@@ -6,7 +6,7 @@ it('rehydrates a JSON AST', () => {
   let cssWithMap = postcss().process(
     '.foo { color: red; font-size: 12pt; } /* abc */ @media (width: 60em) { }',
     {
-      from: undefined,
+      from: 'x.css',
       map: {
         inline: true
       },
@@ -24,6 +24,17 @@ it('rehydrates a JSON AST', () => {
   rehydrated.nodes[0].remove()
 
   expect(rehydrated.nodes).toHaveLength(3)
+
+  expect(
+    postcss().process(rehydrated, {
+      from: undefined,
+      map: {
+        inline: true
+      },
+      stringifier: postcss.stringify
+    }).css
+  ).toBe(`/* abc */ @media (width: 60em) { }
+/*# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbInguY3NzIl0sIm5hbWVzIjpbXSwibWFwcGluZ3MiOiJBQUFzQyxRQUFRLEVBQUUsdUJBQXVCIiwiZmlsZSI6InRvLmNzcyIsInNvdXJjZXNDb250ZW50IjpbIi5mb28geyBjb2xvcjogcmVkOyBmb250LXNpemU6IDEycHQ7IH0gLyogYWJjICovIEBtZWRpYSAod2lkdGg6IDYwZW0pIHsgfSJdfQ== */`)
 })
 
 it('throws when rehydrating an invalid JSON AST', () => {

test/node.test.ts

@@ -292,6 +292,7 @@ it('toJSON() converts custom properties', () => {
     nodes: [],
     raws: {},
     _hack: 'hack',
+    inputs: [],
     _cache: [1]
   })
 })