Add compatibility layer for extensions relying on old compiler

src/compiler/enums.js

@@ -103,6 +103,7 @@ const StackOpcode = {
     DEBUGGER: 'tw.debugger',
     VISUAL_REPORT: 'visualReport',
     COMPATIBILITY_LAYER: 'compat',
+    OLD_COMPILER_COMPATIBILITY_LAYER: 'oldCompiler',
 
     HAT_EDGE: 'hat.edge',
     HAT_PREDICATE: 'hat.predicate',
@@ -201,6 +202,7 @@ const InputOpcode = {
     CAST_COLOR: 'cast.toColor',
 
     COMPATIBILITY_LAYER: 'compat',
+    OLD_COMPILER_COMPATIBILITY_LAYER: 'oldCompiler',
 
     LOOKS_BACKDROP_NUMBER: 'looks.backdropNumber',
     LOOKS_BACKDROP_NAME: 'looks.backdropName',

src/compiler/irgen.js

@@ -14,6 +14,7 @@ const {
     IntermediateScript,
     IntermediateRepresentation
 } = require('./intermediate');
+const oldCompilerCompatiblity = require('./old-compiler-compatibility.js');
 
 /**
  * @fileoverview Generate intermediate representations from Scratch blocks.
@@ -96,6 +97,12 @@ class ScriptTreeGenerator {
                 }
             }
         }
+
+        this.oldCompilerStub = (
+            oldCompilerCompatiblity.enabled ?
+                new oldCompilerCompatiblity.ScriptTreeGeneratorStub(this) :
+                null
+        );
     }
 
     setProcedureVariant (procedureVariant) {
@@ -199,6 +206,13 @@ class ScriptTreeGenerator {
      * @returns {IntermediateInput} Compiled input node for this input.
      */
     descendInput (block, preserveStrings = false) {
+        if (this.oldCompilerStub) {
+            const oldCompilerResult = this.oldCompilerStub.descendInputFromNewCompiler(block);
+            if (oldCompilerResult) {
+                return oldCompilerResult;
+            }
+        }
+
         switch (block.opcode) {
         case 'colour_picker':
             return this.createConstantInput(block.fields.COLOUR.value, true);
@@ -593,6 +607,13 @@ class ScriptTreeGenerator {
      * @returns {IntermediateStackBlock} Compiled node for this block.
      */
     descendStackedBlock (block) {
+        if (this.oldCompilerStub) {
+            const oldCompilerResult = this.oldCompilerStub.descendStackedBlockFromNewCompiler(block);
+            if (oldCompilerResult) {
+                return oldCompilerResult;
+            }
+        }
+
         switch (block.opcode) {
         case 'control_all_at_once':
             // In Scratch 3, this block behaves like "if 1 = 1"

src/compiler/jsgen.js

@@ -6,6 +6,7 @@ const VariablePool = require('./variable-pool');
 const jsexecute = require('./jsexecute');
 const environment = require('./environment');
 const {StackOpcode, InputOpcode, InputType} = require('./enums.js');
+const oldCompilerCompatibility = require('./old-compiler-compatibility.js');
 
 // These imports are used by jsdoc comments but eslint doesn't know that
 /* eslint-disable no-unused-vars */
@@ -124,6 +125,8 @@ class JSGenerator {
         this.isInHat = false;
 
         this.debug = this.target.runtime.debug;
+
+        this.oldCompilerStub = new oldCompilerCompatibility.JSGeneratorStub(this);
     }
 
     /**
@@ -198,6 +201,9 @@ class JSGenerator {
             // Compatibility layer inputs never use flags.
             return `(${this.generateCompatibilityLayerCall(node, false)})`;
 
+        case InputOpcode.OLD_COMPILER_COMPATIBILITY_LAYER:
+            return this.oldCompilerStub.descendInputFromNewCompiler(block);
+
         case InputOpcode.CONSTANT:
             if (block.isAlwaysType(InputType.NUMBER)) {
                 if (typeof node.value !== 'number') throw new Error(`JS: '${block.type}' type constant had ${typeof node.value} type value. Expected number.`);
@@ -540,6 +546,9 @@ class JSGenerator {
             break;
         }
 
+        case InputOpcode.OLD_COMPILER_COMPATIBILITY_LAYER:
+            return this.oldCompilerStub.descendStackedBlockFromNewCompiler(block);
+
         case StackOpcode.HAT_EDGE:
             this.isInHat = true;
             this.source += '{\n';