start WAT

src/wasm/wat.ts

@@ -0,0 +1,116 @@
+// This module converts the Wasm definitions to the WAT
+// WebAssembly text format for easier debugging and inspection.
+
+import {
+  Func,
+  Functype as FuncType,
+  GlobalType,
+  Import,
+  Instr,
+  Limits,
+  Module,
+  TableType as TableType,
+  Valtype as ValType,
+} from "./defs";
+
+const INLINE_SYM = Symbol.for("inline");
+
+type Sexpr = string | number | Sexpr[] | { inline: Symbol; items: Sexpr[] };
+
+export function writeModuleWat(module: Module) {
+  const sexprs = sexprModule(module);
+  console.dir(sexprs, { depth: 100 });
+}
+
+// base
+
+function sexprString(s: string): Sexpr {
+  // TODO: escaping
+  return `"$${s}"`;
+}
+
+// types
+
+function sexprValtype(type: ValType): Sexpr {
+  return type;
+}
+
+function sexprFuncType(type: FuncType): Sexpr {
+  return ["func", ["param", ...type.params], ["result", ...type.returns]];
+}
+
+function sexprLimits(limits: Limits): Sexpr {
+  return { inline: INLINE_SYM, items: [limits.min, limits.max] };
+}
+
+function sexprTableType(type: TableType): Sexpr {
+  todo();
+}
+
+function sexprGlobalType(type: GlobalType): Sexpr {
+  return type.mut === "const"
+    ? sexprValtype(type.type)
+    : ["mut", sexprValtype(type.type)];
+}
+
+// instrs
+
+function sexprInstr(instr: Instr): Sexpr {
+  todo();
+}
+
+// modules
+
+function sexprType(type: FuncType): Sexpr {
+  return ["type", sexprFuncType(type)];
+}
+
+function sexprImport(import_: Import): Sexpr {
+  const desc = import_.desc;
+  let importDesc: Sexpr;
+  switch (desc.kind) {
+    case "func":
+      importDesc = ["type", desc.type];
+      break;
+    case "table":
+      importDesc = sexprTableType(desc.type);
+      break;
+    case "memory":
+      importDesc = sexprLimits(desc.type);
+      break;
+    case "global":
+      importDesc = sexprGlobalType(desc.type);
+      break;
+  }
+
+  return [
+    "import",
+    sexprString(import_.module),
+    sexprString(import_.name),
+    [desc.kind, importDesc],
+  ];
+}
+
+function sexprFunction(func: Func): Sexpr {
+  return [
+    "func",
+    ...(func._name ? [func._name] : []),
+    ["type", func.type],
+    ...func.locals.map((local) => ["local", sexprValtype(local)]),
+    ...func.body.map((instr) => sexprInstr(instr)),
+  ];
+}
+
+function sexprModule(module: Module): Sexpr {
+  return [
+    "module",
+    ...(module._name ? [module._name] : []),
+    ...module.types.map(sexprType),
+    ...module.imports.map(sexprImport),
+    ...module.funcs.map(sexprFunction),
+  ];
+}
+
+function todo(): never {
+  throw new Error("todo");
+}