feat(parse): spruce up this package to make it useful

packages/parse/src/all.js

@@ -0,0 +1,5 @@
+export { default as bootPeg } from './boot-peg.js';
+export { default as bootPegAst } from './boot-pegast.js';
+export { default as makePeg } from './quasi-peg.js';
+export { default as makeJSON } from './quasi-json.js';
+export { default as makeJustin } from './quasi-justin.js';

packages/parse/src/boot-peg.js

@@ -157,7 +157,9 @@ ${self.template.raw.reduce((prior, r, i) => {
 }, '')}
 -------
 ${failStr}`);
-  console.error(`Syntax error ${tokStr}`);
+  const err = Error(`Syntax: cannot parse ${tokStr}`);
+  err.stack = undefined;
+  throw err;
 };
 
 /**
@@ -690,7 +692,7 @@ pos = ${posSrc};`;
         wm.set(template, quasiRest);
       }
       if (typeof quasiRest !== 'function') {
-        console.error(`${typeof quasiRest}: ${quasiRest}`);
+        return quasiRest;
       }
       return quasiRest(...subs);
     };
@@ -771,7 +773,7 @@ pos = ${posSrc};`;
         /**
          * @template X
          * @param {ParserOptions} options
-         * @returns {IPegTag<IParserTag<X>>}
+         * @returns {IPegTag<IParserTag<X, any>>}
          */
         const makeExtensionTag = (options = {}) => {
           /**

packages/parse/src/main.js

@@ -1 +1,20 @@
-export { default as bootPeg } from './boot-peg.js';
+import { bootPeg, bootPegAst, makePeg, makeJSON, makeJustin } from './all.js';
+
+export { bootPeg };
+
+// The currently-supported parse tags.
+
+/**
+ * Parser template tag that creates new parser template tags from PEGs.
+ */
+export const peg = bootPeg(makePeg, bootPegAst);
+
+/**
+ * JSON parser template tag.
+ */
+export const json = makeJSON(peg);
+
+/**
+ * Justin parser template tag.
+ */
+export const justin = makeJustin(peg.extends(json));

packages/parse/src/peg.d.ts

@@ -31,7 +31,7 @@ interface ParserOptions {
   debug?: boolean;
 }
 
-interface IParserTag<T = any, U = any> {
+interface IParserTag<T = any, U = { holes: any[]; ast: any }> {
   (template: TemplateStringsArray, ...args: T[]): U;
   options(opts: Partial<ParserOptions>): IParserTag<T, U>;
   parserCreator: PegParserCreator;

packages/parse/src/quasi-json.js

@@ -16,7 +16,7 @@ const makeJSON = peg => {
   const { FAIL, HOLE, SKIP } = peg;
   return peg`
 # to be overridden or inherited
-start <- _WS assignExpr _EOF                ${v => () => v};
+start <- _WS assignExpr _EOF          ${ast => (...holes) => ({ ast, holes })};
 
 # to be extended
 primaryExpr <- dataStructure;
@@ -116,15 +116,16 @@ hex <- digit / [a-fA-F];
 
 NUMBER <- < int frac? exp? > _WSN;
 
-int <- [1-9] digit+
+int <- [1-9] digits
 / digit
-/ MINUS digit
-/ MINUS [1-9] digit+;
+/ MINUS [1-9] digits
+/ MINUS digit;
 
 digit <- [0-9];
+digits <- digit*;
 
-frac <- '.' digit+;
-exp <- [Ee] [+\-]? digit+;
+frac <- '.' digits;
+exp <- [Ee] [+\-]? digits;
 
 # _WSN is whitespace or a non-ident character.
 _WSN <- ~[$A-Za-z_] _WS    ${_ => SKIP};

packages/parse/src/quasi-justin.js

@@ -9,7 +9,8 @@
 //   * multi-line strings (via template literals).
 //   * undefined.
 //   * includes all floating point values: NaN, Infinity, -Infinity
-//   * will include BigInt once available.
+//   * includes BigInt literals: 123n
+//   * numbers and bigints can have optional underscores: 1_000_000n
 
 // Justin also includes most pure JavaScript expressions. Justin does not
 // include function expressions or variable or function
@@ -22,9 +23,9 @@
 // See https://github.com/endojs/Jessie/blob/main/README.md
 // for documentation of the Jessie grammar.
 
-// Justin is defined to be extended into the Chainmail grammar, to
-// provide its expression language in a JS-like style. Chainmail
-// expressions need to be pure and should be terminating.
+// Justin is also intended to be extended into the Chainmail grammar, to provide
+// its expression language in a JS-like style. Chainmail expressions need to be
+// pure and should be terminating.
 
 /// <reference path="./peg.d.ts"/>
 
@@ -70,7 +71,7 @@ const makeJustin = peg => {
   const { SKIP } = peg;
   return peg`
     # to be overridden or inherited
-    start <- _WS assignExpr _EOF                       ${v => () => v};
+    start <- _WS assignExpr _EOF ${ast => (...holes) => ({ ast, holes })};
 
     # A.1 Lexical Grammar
 
@@ -82,6 +83,16 @@ const makeJustin = peg => {
     RIGHT_PAREN <- ")" _WS;
     STARSTAR <- "**" _WS;
 
+    # Allow optional underscore digit separators.
+    digits <- super.digit ** ("_"?);
+    NUMBER <- super.NUMBER ${ns => ns.replaceAll('_', '')};
+
+    # BigInts are not supported in JSON, but they are in Justin.
+    bigintLiteral <- < int > "n" _WSN ${ns => [
+      'data',
+      BigInt(ns.replaceAll('_', '')),
+    ]};
+
     # Define Javascript-style comments.
     _WS <- super._WS (EOL_COMMENT / MULTILINE_COMMENT)?   ${_ => SKIP};
     EOL_COMMENT <- "//" (~[\n\r] .)* _WS;
@@ -144,11 +155,14 @@ const makeJustin = peg => {
     / "interface" / "private" / "public") _WSN;
 
     # Quasiliterals aka template literals
-    QUASI_CHAR <- "\\" . / ~"\`" .;
-    QUASI_ALL <- "\`" < (~"\${" QUASI_CHAR)* > "\`" _WS;
-    QUASI_HEAD <- "\`" < (~"\${" QUASI_CHAR)* > "\${" _WS;
-    QUASI_MID <- "}" < (~"\${" QUASI_CHAR)* > "\${" _WS;
-    QUASI_TAIL <- "}" < (~"\${" QUASI_CHAR)* > "\`" _WS;
+    QCHAR <- "\\" . / ~QQUOTE .;
+    QQUOTE <- "\`";
+    QHOLE <- "\${";
+    QHOLE_END <- "}";
+    QUASI_ALL <- QQUOTE < (~QHOLE QCHAR)* > QQUOTE _WS;
+    QUASI_HEAD <- QQUOTE < (~QHOLE QCHAR)* > QHOLE _WS;
+    QUASI_MID <- QHOLE_END < (~QHOLE QCHAR)* > QHOLE _WS;
+    QUASI_TAIL <- QHOLE_END < (~QHOLE QCHAR)* > QQUOTE _WS;
 
 
     # A.2 Expressions
@@ -158,6 +172,7 @@ const makeJustin = peg => {
 
     dataStructure <-
       undefined
+    / bigintLiteral
     / super.dataStructure;
 
     # Optional trailing commas.