source: frontend/node_modules/webpack/lib/wasm-sync/WebAssemblyParser.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

const t = require("@webassemblyjs/ast");
const { moduleContextFromModuleAST } = require("@webassemblyjs/ast");
const { decode } = require("@webassemblyjs/wasm-parser");
const Parser = require("../Parser");
const StaticExportsDependency = require("../dependencies/StaticExportsDependency");
const WebAssemblyExportImportedDependency = require("../dependencies/WebAssemblyExportImportedDependency");
const WebAssemblyImportDependency = require("../dependencies/WebAssemblyImportDependency");

/** @typedef {import("@webassemblyjs/ast").ModuleImport} ModuleImport */
/** @typedef {import("../Module").BuildInfo} BuildInfo */
/** @typedef {import("../Module").BuildMeta} BuildMeta */
/** @typedef {import("../Parser").ParserState} ParserState */
/** @typedef {import("../Parser").PreparsedAst} PreparsedAst */

const JS_COMPAT_TYPES = new Set(["i32", "i64", "f32", "f64", "externref"]);

/**
 * Gets js incompatible type.
 * @param {t.Signature} signature the func signature
 * @returns {null | string} the type incompatible with js types
 */
const getJsIncompatibleType = (signature) => {
        for (const param of signature.params) {
                if (!JS_COMPAT_TYPES.has(param.valtype)) {
                        return `${param.valtype} as parameter`;
                }
        }
        for (const type of signature.results) {
                if (!JS_COMPAT_TYPES.has(type)) return `${type} as result`;
        }
        return null;
};

/**
 * TODO why are there two different Signature types?
 * @param {t.FuncSignature} signature the func signature
 * @returns {null | string} the type incompatible with js types
 */
const getJsIncompatibleTypeOfFuncSignature = (signature) => {
        for (const param of signature.args) {
                if (!JS_COMPAT_TYPES.has(param)) {
                        return `${param} as parameter`;
                }
        }
        for (const type of signature.result) {
                if (!JS_COMPAT_TYPES.has(type)) return `${type} as result`;
        }
        return null;
};

const decoderOpts = {
        ignoreCodeSection: true,
        ignoreDataSection: true,

        // this will avoid having to lookup with identifiers in the ModuleContext
        ignoreCustomNameSection: true
};

class WebAssemblyParser extends Parser {
        /**
         * Parses the provided source and updates the parser state.
         * @param {string | Buffer | PreparsedAst} source the source to parse
         * @param {ParserState} state the parser state
         * @returns {ParserState} the parser state
         */
        parse(source, state) {
                if (!Buffer.isBuffer(source)) {
                        throw new Error("WebAssemblyParser input must be a Buffer");
                }

                // flag it as ESM
                /** @type {BuildInfo} */
                (state.module.buildInfo).strict = true;
                /** @type {BuildMeta} */
                (state.module.buildMeta).exportsType = "namespace";

                // parse it
                const program = decode(source, decoderOpts);
                const module = program.body[0];

                const moduleContext = moduleContextFromModuleAST(module);

                // extract imports and exports
                /** @type {string[]} */
                const exports = [];
                const buildMeta = /** @type {BuildMeta} */ (state.module.buildMeta);
                /** @type {Record<string, string> | undefined} */
                let jsIncompatibleExports = (buildMeta.jsIncompatibleExports = undefined);

                /** @typedef {ModuleImport | null} ImportNode */
                /** @type {ImportNode[]} */
                const importedGlobals = [];

                t.traverse(module, {
                        ModuleExport({ node }) {
                                const descriptor = node.descr;

                                if (descriptor.exportType === "Func") {
                                        const funcIdx = descriptor.id.value;

                                        /** @type {t.FuncSignature} */
                                        const funcSignature = moduleContext.getFunction(funcIdx);

                                        const incompatibleType =
                                                getJsIncompatibleTypeOfFuncSignature(funcSignature);

                                        if (incompatibleType) {
                                                if (jsIncompatibleExports === undefined) {
                                                        jsIncompatibleExports =
                                                                /** @type {BuildMeta} */
                                                                (state.module.buildMeta).jsIncompatibleExports = {};
                                                }
                                                jsIncompatibleExports[node.name] = incompatibleType;
                                        }
                                }

                                exports.push(node.name);

                                if (node.descr && node.descr.exportType === "Global") {
                                        const refNode = importedGlobals[node.descr.id.value];
                                        if (refNode) {
                                                const dep = new WebAssemblyExportImportedDependency(
                                                        node.name,
                                                        refNode.module,
                                                        refNode.name,
                                                        /** @type {string} */
                                                        (refNode.descr.valtype)
                                                );

                                                state.module.addDependency(dep);
                                        }
                                }
                        },

                        Global({ node }) {
                                const init = node.init[0];

                                /** @type {ImportNode} */
                                let importNode = null;

                                if (init.id === "get_global") {
                                        const globalIdx = init.args[0].value;

                                        if (globalIdx < importedGlobals.length) {
                                                importNode = importedGlobals[globalIdx];
                                        }
                                }

                                importedGlobals.push(importNode);
                        },

                        ModuleImport({ node }) {
                                /** @type {false | string} */
                                let onlyDirectImport = false;

                                if (t.isMemory(node.descr) === true) {
                                        onlyDirectImport = "Memory";
                                } else if (t.isTable(node.descr) === true) {
                                        onlyDirectImport = "Table";
                                } else if (t.isFuncImportDescr(node.descr) === true) {
                                        const incompatibleType = getJsIncompatibleType(
                                                /** @type {t.Signature} */
                                                (node.descr.signature)
                                        );
                                        if (incompatibleType) {
                                                onlyDirectImport = `Non-JS-compatible Func Signature (${incompatibleType})`;
                                        }
                                } else if (t.isGlobalType(node.descr) === true) {
                                        const type = /** @type {string} */ (node.descr.valtype);
                                        if (!JS_COMPAT_TYPES.has(type)) {
                                                onlyDirectImport = `Non-JS-compatible Global Type (${type})`;
                                        }
                                }

                                const dep = new WebAssemblyImportDependency(
                                        node.module,
                                        node.name,
                                        node.descr,
                                        onlyDirectImport
                                );

                                state.module.addDependency(dep);

                                if (t.isGlobalType(node.descr)) {
                                        importedGlobals.push(node);
                                }
                        }
                });

                state.module.addDependency(new StaticExportsDependency(exports, false));

                return state;
        }
}

module.exports = WebAssemblyParser;