1 files changed, 287 insertions, 0 deletions
diff --git a/node_modules/@webassemblyjs/helper-module-context/src/index.js b/node_modules/@webassemblyjs/helper-module-context/src/index.js
new file mode 100644
index 0000000..e3171de
--- /dev/null
+++ b/node_modules/@webassemblyjs/helper-module-context/src/index.js
@@ -0,0 +1,287 @@
+// TODO(sven): add flow in here
+
+import { isSignature, isNumberLiteral } from "@webassemblyjs/ast";
+import { assert } from "mamacro";
+
+export function moduleContextFromModuleAST(m) {
+  const moduleContext = new ModuleContext();
+
+  assert(m.type === "Module");
+
+  m.fields.forEach(field => {
+    switch (field.type) {
+      case "Start": {
+        moduleContext.setStart(field.index);
+        break;
+      }
+      case "TypeInstruction": {
+        moduleContext.addType(field);
+        break;
+      }
+      case "Func": {
+        moduleContext.addFunction(field);
+        break;
+      }
+      case "Global": {
+        moduleContext.defineGlobal(field);
+        break;
+      }
+      case "ModuleImport": {
+        switch (field.descr.type) {
+          case "GlobalType": {
+            moduleContext.importGlobal(
+              field.descr.valtype,
+              field.descr.mutability
+            );
+            break;
+          }
+          case "Memory": {
+            moduleContext.addMemory(
+              field.descr.limits.min,
+              field.descr.limits.max
+            );
+            break;
+          }
+          case "FuncImportDescr": {
+            moduleContext.importFunction(field.descr);
+            break;
+          }
+
+          case "Table": {
+            // FIXME(sven): not implemented yet
+            break;
+          }
+
+          default:
+            throw new Error(
+              "Unsupported ModuleImport of type " +
+                JSON.stringify(field.descr.type)
+            );
+        }
+        break;
+      }
+      case "Memory": {
+        moduleContext.addMemory(field.limits.min, field.limits.max);
+        break;
+      }
+    }
+  });
+
+  return moduleContext;
+}
+
+/**
+ * Module context for type checking
+ */
+export class ModuleContext {
+  constructor() {
+    this.funcs = [];
+    this.funcsOffsetByIdentifier = [];
+
+    this.types = [];
+
+    this.globals = [];
+    this.globalsOffsetByIdentifier = [];
+
+    this.mems = [];
+
+    // Current stack frame
+    this.locals = [];
+    this.labels = [];
+    this.return = [];
+
+    this.debugName = "unknown";
+
+    this.start = null;
+  }
+
+  /**
+   * Set start segment
+   */
+  setStart(index) {
+    this.start = index.value;
+  }
+
+  /**
+   * Get start function
+   */
+  getStart() {
+    return this.start;
+  }
+
+  /**
+   * Reset the active stack frame
+   */
+  newContext(debugName, expectedResult) {
+    this.locals = [];
+    this.labels = [expectedResult];
+    this.return = expectedResult;
+    this.debugName = debugName;
+  }
+
+  /**
+   * Functions
+   */
+  addFunction(func /*: Func*/) {
+    // eslint-disable-next-line prefer-const
+    let { params: args = [], results: result = [] } = func.signature || {};
+
+    args = args.map(arg => arg.valtype);
+
+    this.funcs.push({ args, result });
+
+    if (typeof func.name !== "undefined") {
+      this.funcsOffsetByIdentifier[func.name.value] = this.funcs.length - 1;
+    }
+  }
+
+  importFunction(funcimport) {
+    if (isSignature(funcimport.signature)) {
+      // eslint-disable-next-line prefer-const
+      let { params: args, results: result } = funcimport.signature;
+      args = args.map(arg => arg.valtype);
+
+      this.funcs.push({ args, result });
+    } else {
+      assert(isNumberLiteral(funcimport.signature));
+
+      const typeId = funcimport.signature.value;
+      assert(this.hasType(typeId));
+
+      const signature = this.getType(typeId);
+      this.funcs.push({
+        args: signature.params.map(arg => arg.valtype),
+        result: signature.results
+      });
+    }
+
+    if (typeof funcimport.id !== "undefined") {
+      // imports are first, we can assume their index in the array
+      this.funcsOffsetByIdentifier[funcimport.id.value] = this.funcs.length - 1;
+    }
+  }
+
+  hasFunction(index) {
+    return typeof this.getFunction(index) !== "undefined";
+  }
+
+  getFunction(index) {
+    if (typeof index !== "number") {
+      throw new Error("getFunction only supported for number index");
+    }
+
+    return this.funcs[index];
+  }
+
+  getFunctionOffsetByIdentifier(name) {
+    assert(typeof name === "string");
+
+    return this.funcsOffsetByIdentifier[name];
+  }
+
+  /**
+   * Labels
+   */
+  addLabel(result) {
+    this.labels.unshift(result);
+  }
+
+  hasLabel(index) {
+    return this.labels.length > index && index >= 0;
+  }
+
+  getLabel(index) {
+    return this.labels[index];
+  }
+
+  popLabel() {
+    this.labels.shift();
+  }
+
+  /**
+   * Locals
+   */
+  hasLocal(index) {
+    return typeof this.getLocal(index) !== "undefined";
+  }
+
+  getLocal(index) {
+    return this.locals[index];
+  }
+
+  addLocal(type) {
+    this.locals.push(type);
+  }
+
+  /**
+   * Types
+   */
+  addType(type) {
+    assert(type.functype.type === "Signature");
+    this.types.push(type.functype);
+  }
+
+  hasType(index) {
+    return this.types[index] !== undefined;
+  }
+
+  getType(index) {
+    return this.types[index];
+  }
+
+  /**
+   * Globals
+   */
+  hasGlobal(index) {
+    return this.globals.length > index && index >= 0;
+  }
+
+  getGlobal(index) {
+    return this.globals[index].type;
+  }
+
+  getGlobalOffsetByIdentifier(name) {
+    assert(typeof name === "string");
+
+    return this.globalsOffsetByIdentifier[name];
+  }
+
+  defineGlobal(global /*: Global*/) {
+    const type = global.globalType.valtype;
+    const mutability = global.globalType.mutability;
+
+    this.globals.push({ type, mutability });
+
+    if (typeof global.name !== "undefined") {
+      this.globalsOffsetByIdentifier[global.name.value] =
+        this.globals.length - 1;
+    }
+  }
+
+  importGlobal(type, mutability) {
+    this.globals.push({ type, mutability });
+  }
+
+  isMutableGlobal(index) {
+    return this.globals[index].mutability === "var";
+  }
+
+  isImmutableGlobal(index) {
+    return this.globals[index].mutability === "const";
+  }
+
+  /**
+   * Memories
+   */
+  hasMemory(index) {
+    return this.mems.length > index && index >= 0;
+  }
+
+  addMemory(min, max) {
+    this.mems.push({ min, max });
+  }
+
+  getMemory(index) {
+    return this.mems[index];
+  }
+}