Throw errors when imports are used in unsupported formats

CHANGELOG.md

@@ -13,6 +13,7 @@ Released: TBD
 ### New features
 
 ### Bug fixes
+- [#490](https://github.com/peggyjs/peggy/issues/490) Throw error when imports are used in unsupported formats.  Supported formats are now only "es" and "commonjs".
 
 4.0.1
 -----

docs/documentation.html

@@ -746,8 +746,16 @@ <h3 id="importing-external-rules">Importing External Rules</h3>
        grammar, NOT the source.  Grammars MUST be compiled by a version that
        supports imports in order to be imported.  Only rules that are allowed
        start rules are valid.  It can be useful to specify
-       <code>--allowed-start-rules \*</code> in library grammars. All of the
-       following are valid:</p>
+       <code>--allowed-start-rules \*</code> in library grammars.  Imports are
+       only valid in output formats "es" and "commonjs".  If you
+       use imports, you should use <code>{ output: "source" }</code>; the default
+       output of "parser" will call `eval` on the source which fails immediately
+       for some formats (e.g. "es") and will not find modules in the expected
+       places for others (e.g. "commonjs").  The
+       <a href="https://github.com/peggyjs/from-mem/">from-mem</a> project is
+       used by the Peggy CLI to resolve these issues, but note well its
+       relatively severe limitations.</p>
+       <p>All of the following are valid:</p>
     <ul>
       <li><code>import * as num from "number.js" // Call with num.number</code></li>
       <li><code>import num from "number.js" // Calls the default rule</code></li>

lib/compiler/passes/generate-js.js

@@ -1451,6 +1451,10 @@ function generateJS(ast, options) {
 
     const generators = {
       bare() {
+        if ((Object.keys(dependencies).length > 0)
+            || (ast.imports.length > 0)) {
+          throw new Error("Dependencies not supported in format 'bare'.");
+        }
         return [
           ...generateGeneratedByComment(),
           "(function() {",
@@ -1564,12 +1568,12 @@ function generateJS(ast, options) {
       },
 
       amd() {
+        if (ast.imports.length > 0) {
+          throw new Error("Imports are not supported in format 'amd'.");
+        }
+
         const dependencyVars = Object.keys(dependencies);
         const dependencyIds = dependencyVars.map(v => dependencies[v]);
-        for (let i = 0; i < ast.imports.length; i++) {
-          dependencyVars.push(gi(i));
-          dependencyIds.push(ast.imports[i].from.module);
-        }
         const deps = "["
           + dependencyIds.map(
             id => "\"" + stringEscape(id) + "\""
@@ -1590,6 +1594,14 @@ function generateJS(ast, options) {
       },
 
       globals() {
+        if ((Object.keys(dependencies).length > 0)
+            || (ast.imports.length > 0)) {
+          throw new Error("Dependencies not supported in format 'globals'.");
+        }
+        if (!options.exportVar) {
+          throw new Error("No export variable defined");
+        }
+
         return [
           ...generateGeneratedByComment(),
           "(function(root) {",
@@ -1603,12 +1615,12 @@ function generateJS(ast, options) {
       },
 
       umd() {
+        if (ast.imports.length > 0) {
+          throw new Error("Imports are not supported in format 'umd'.");
+        }
+
         const dependencyVars = Object.keys(dependencies);
         const dependencyIds = dependencyVars.map(v => dependencies[v]);
-        for (let i = 0; i < ast.imports.length; i++) {
-          dependencyVars.push(gi(i));
-          dependencyIds.push(ast.imports[i].from.module);
-        }
         const deps = "["
           + dependencyIds.map(
             id => "\"" + stringEscape(id) + "\""
@@ -1628,7 +1640,7 @@ function generateJS(ast, options) {
           "    module.exports = factory(" + requires + ");"
         );
 
-        if (options.exportVar !== null) {
+        if (options.exportVar) {
           parts.push(
             "  } else {",
             "    root." + options.exportVar + " = factory();"

test/cli/run.spec.ts

@@ -535,6 +535,18 @@ Options:
       expected: /c = require\("commander"\)/,
     });
 
+    await exec({
+      args: ["-D", '{"c": "commander", "jest": "jest"}', "--format", "amd"],
+      stdin: "foo = '1' { return new c.Command(); }",
+      expected: /define\(\["commander", "jest"\]/,
+    });
+
+    await exec({
+      args: ["-D", '{"c": "commander", "jest": "jest"}', "--format", "umd", "-e", "foo"],
+      stdin: "foo = '1' { return new c.Command(); }",
+      expected: /define\(\["commander", "jest"\]/,
+    });
+
     await exec({
       args: ["-D", '{"c": "commander"}', "-d", "c:jest"],
       stdin: "foo = '1' { return c.run(); }",
@@ -566,6 +578,13 @@ Options:
       expected: /^\s*root\.football = /m,
     });
 
+    await exec({
+      args: ["--format", "globals"],
+      stdin: "foo = '1'",
+      exitCode: 1,
+      expected: "Error parsing grammar\nNo export variable defined\n",
+    });
+
     await exec({
       args: ["--export-var"],
       stdin: "foo = '1'",
@@ -585,7 +604,7 @@ Options:
 
   it("handles extra options", async() => {
     await exec({
-      args: ["--extra-options", '{"format": "amd"}'],
+      args: ["-d", "fs", "--extra-options", '{"format": "amd"}'],
       stdin: 'foo = "1"',
       expected: /^define\(/m,
     });
@@ -1221,7 +1240,7 @@ Error: Expected "1" but end of input found.
         error: /Unsupported output format/,
       });
       await exec({
-        args: ["--format", "globals", "-t", "1", grammar],
+        args: ["--format", "globals", "-e", "foo", "-t", "1", grammar],
         error: /Unsupported output format/,
       });
       await exec({
@@ -1263,6 +1282,30 @@ error: Rule "unknownRule" is not defined
 
     const { parse } = await import(impjs);
     expect(parse("baz")).toBe("baz");
+
+    await exec({
+      args: [imps, "--format", "globals"],
+      exitCode: 1,
+      expected: "Error parsing grammar\nDependencies not supported in format 'globals'.\n",
+    });
+
+    await exec({
+      args: [imps, "--format", "bare"],
+      exitCode: 1,
+      expected: "Error parsing grammar\nDependencies not supported in format 'bare'.\n",
+    });
+
+    await exec({
+      args: [imps, "--format", "amd"],
+      exitCode: 1,
+      expected: "Error parsing grammar\nImports are not supported in format 'amd'.\n",
+    });
+
+    await exec({
+      args: [imps, "--format", "umd"],
+      exitCode: 1,
+      expected: "Error parsing grammar\nImports are not supported in format 'umd'.\n",
+    });
   });
 
   it("produces library-style output", async() => {