Add support for --depth. Fixes #21

.gitattributes

@@ -0,0 +1,13 @@
+*.js text eol=lf
+*.ts text eol=lf
+*.json text eol=lf
+*.html text eol=lf
+*.css text eol=lf
+*.map text eol=lf
+*.peggy text eol=lf
+*.pegjs text eol=lf
+*.svg text eol=lf
+*.png binary
+*.jpg binary
+*.ico binary
+*.snap binary

README.md

@@ -27,6 +27,8 @@ Options:
   -a,--action              Wrap actions in a box
   -c,--css [file name]     With no file name, outputs the default CSS.  With a
                            filename, substitutes the CSS in that file.
+  -d,--depth <number>      Maximum depth to expand references (set to Infinity
+                           with --expand).
   -e,--expand              Expand rule references
   -o,--output <file name>  File in which to save output
   -s,--start <rule name>   Rule to start with
@@ -35,7 +37,8 @@ Options:
 
 ## More control
 
-To change the look and feel of the output, you can output the default CSS that will be placed in the SVG:
+To change the look and feel of the output, you can output the default CSS that
+will be placed in the SVG:
 
 ```sh
 peggy-tracks -c > my.css
@@ -51,7 +54,9 @@ Generates this:
 
 ![comments-expanded](./test/output/action.svg)
 
-Note that the `--action` flag has created extra boxes around parts of the grammar, that when moused over show the code that will be executed when the fragment matches.
+Note that the `--action` flag has created extra boxes around parts of the
+grammar, that when moused over show the code that will be executed when the
+fragment matches.
 
 ## API
 

lib/cli.js

@@ -1,8 +1,8 @@
+import { Command, Option } from "commander";
 import { createReadStream, createWriteStream } from "fs";
 import { defaultCSS, tracks } from "./index.js";
 import { format, join, parse } from "path";
 import { readFile, stat } from "fs/promises";
-import { Command } from "commander";
 
 function readStream(stream) {
   return new Promise((resolve, reject) => {
@@ -63,6 +63,7 @@ export default class CliCommand extends Command {
       .argument("[input_file]")
       .option("-a,--action", "Wrap actions in a box")
       .option("-c,--css [file name]", "With no file name, outputs the default CSS.  With a filename, substitutes the CSS in that file.")
+      .addOption(new Option("-d,--depth <number>", "Maximum depth to expand references (set to Infinity with --expand).").conflicts("expand"))
       .option("-e,--expand", "Expand rule references")
       .option("-o,--output <file name>", "File in which to save output")
       .option("-s,--start <rule name>", "Rule to start with");
@@ -93,6 +94,17 @@ export default class CliCommand extends Command {
       delete opts.css;
     }
 
+    let depth = 0;
+    if (opts.expand === true) {
+      depth = Infinity;
+    } else if (typeof opts.depth === "string") {
+      depth = parseInt(opts.depth, 10);
+      if (isNaN(depth) || depth < 0) {
+        this.error(`"--depth" must be positive integer, got "${opts.depth}"`);
+      }
+    }
+    opts.depth = depth;
+
     const files = this.args.length ? this.args : ["-"];
     for (const grammarSource of files) {
       const stream = (grammarSource === "-")

lib/index.js

@@ -28,7 +28,6 @@ import peggy from "peggy";
  * @property {string} [start] The rule name to start with.
  *   Defaults to first rule in the grammar.
  * @property {boolean} [action=false] Create action blocks.
- * @property {boolean} [expand=false] Expand rule references.
  * @property {object} parserOptions Peggy parser options.  Most important
  *   is "grammarSource".
  */
@@ -135,9 +134,15 @@ const visit = peggy.compiler.visitor.build({
     });
   },
   rule_ref(node, context) {
-    return context.opts.expand
-      ? visit(asts.findRule(context.grammar, node.name), context)
-      : new NonTerminal(node.name, { cls: "rule-ref" });
+    let res = null;
+    if (context.opts.depth > 0) {
+      context.opts.depth--;
+      res = visit(asts.findRule(context.grammar, node.name), context);
+      context.opts.depth++;
+    } else {
+      res = new NonTerminal(node.name, { cls: "rule-ref" });
+    }
+    return res;
   },
   library_ref(node) {
     return new NonTerminal(`${node.library}.${node.name}`, { cls: "library_ref" });
@@ -166,8 +171,7 @@ const visit = peggy.compiler.visitor.build({
  * Generate a railroad track diagram from a grammer
  *
  * @param {TrackOptions} opts
- * @return {Diagram|ComplexDiagram
- }
+ * @return {Diagram|ComplexDiagram}
  */
 export function tracks(opts) {
   const context = {

test/cli.test.js

@@ -50,18 +50,7 @@ test("cli help", async t => {
     defaultOutputStream,
   });
 
-  t.is(defaultOutputStream.read(), `\
-Usage: peggy-tracks [options] [input_file]
-
-Options:
-  -a,--action              Wrap actions in a box
-  -c,--css [file name]     With no file name, outputs the default CSS.  With a
-                           filename, substitutes the CSS in that file.
-  -e,--expand              Expand rule references
-  -o,--output <file name>  File in which to save output
-  -s,--start <rule name>   Rule to start with
-  -h, --help               display help for command
-`);
+  t.snapshot(defaultOutputStream.read());
 
   const errorStream = new Buf();
   await exec(t, ["-s"], "commander.optionMissingArgument", {
@@ -178,3 +167,13 @@ test("more examples", async t => {
   await exec(t, ["-e", "-o", fullURL, inp]);
   t.snapshot(await readFile(fullURL, "utf8"));
 });
+
+test("depth", async t => {
+  const inp = url.fileURLToPath(new URL("test.peggy", import.meta.url));
+
+  for (let i = 0; i < 5; i++) {
+    const fullURL = url.fileURLToPath(new URL(`output/depth${i}.svg`, import.meta.url));
+    await exec(t, ["-d", String(i), "-o", fullURL, inp]);
+    t.snapshot(await readFile(fullURL, "utf8"));
+  }
+});