Initial import.

diff --git a/.gitignore b/.gitignore
new file mode 100644 (file)
index 0000000..c169afd
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+build
+node_modules
+*.min.js

diff --git a/COPYING.txt b/COPYING.txt
new file mode 100644 (file)
index 0000000..d159169
--- /dev/null
+++ b/COPYING.txt
@@ -0,0 +1,339 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
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+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
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+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
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+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
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+    (at your option) any later version.
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+    This is free software, and you are welcome to redistribute it
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+The hypothetical commands `show w' and `show c' should show the appropriate
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+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
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+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.

diff --git a/Makefile b/Makefile
new file mode 100644 (file)
index 0000000..4084442
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,61 @@
+#!/usr/bin/make -f
+
+PKGNAME := rrr
+
+all:
+       $(info Interesting targets:)
+       $(info    lint - validate source (with jshint))
+       $(info    test - run tests (with jstest))
+       $(info    ugly - generate minified source files)
+       $(info    dist - generate redistributables (if git tagged))
+       $(info )
+       $(info (Running these may download packages from npm.))
+       $(info )
+       @:
+
+
+SOURCES := rrr.js term.js
+JSTEST_SOURCES += $(SOURCES)
+
+include javascript.mk
+
+GIT ?= git
+git-describe = $(shell $(GIT) describe --tags --always $1)
+
+UGLIFIED := $(call uglify-stampify,$(SOURCES))
+
+JSHINTCONFIG := tests/jshint.config
+JSSTAMPDIR := build/stamp
+
+TESTS := $(wildcard tests/*.js)
+LINTS := $(call jshint-stampify,$(SOURCES) $(TESTS))
+TEST_TARGETS = $(patsubst %.js,build/stamp/tests/%.js.test,$(SOURCES))
+
+.DELETE_ON_ERROR:
+.PHONY: all check lint test ugly dist clean distclean install 
+
+check: lint test
+
+lint: $(LINTS)
+
+test: $(TEST_TARGETS)
+
+ugly: check $(UGLIFIED)
+
+dist: check
+
+clean:
+       $(RM) -r build
+       $(RM) $(UGLIFIED)
+
+distclean: clean
+       $(RM) -r node_modules
+
+install: check
+       $(NPM) install -g .
+
+dist: check build/dist/$(PKGNAME)-$(call git-describe).tar.gz
+
+$(PKGNAME)-%.tar.gz: | .git
+       @mkdir -p $(@D)
+       $(GIT) archive --prefix=$(PKGNAME)-$(*F)/ --output=$@ $(*F)

diff --git a/README.md b/README.md
new file mode 100644 (file)
index 0000000..eaf26ff
--- /dev/null
+++ b/README.md
@@ -0,0 +1,121 @@
+# Recursive Random Rewrites
+
+RRR is a JavaScript library which repeatedly applies replacements to a
+string. This can be used to generate a wide variety of random text. It
+is sort of like, but is not, an [L-system][], a [Markov machine][], or
+a [stochastic grammar][].
+
+RRR works by specifying a grammar using [BNF][]-like rules (easily
+specified with JSON). An object providing the production rules,
+mapping the names to possible expansions, is provided to the `Grammar`
+constructor. Possible productions are specified as an object mapping a
+production to a numeric weight.
+
+The `Grammar`'s `expand` method then randomly expands an input string
+based on the grammar specified.
+
+For convenience, possible productions may also be provided as a list
+or string, in which case each item has equal weight. RRR also provides
+some syntactic sugar for repetition:
+
+* `<A>{n}` - Repeat rule `A` `n` times.
+* `<A>{n,m}` - Repeat rule `A` a random number of times between `n`
+  and `m` (uniformly, inclusive).
+* `<A>?` - Produce rule `A` ½ of the time, and nothing ½ of the time.
+* `<A>*` - Produce nothing ½ of the time, `<A>` ¼ of the time,
+  `<A><A>` ⅛ of the time, and so on.
+* `<A>+` - Produce `<A>` ½ of the time, `<A><A>` ¼ of the time,
+  `<A><A><A>` ⅛ of the time, and so on.
+
+Repetition patterns can also be specified with a space after the rule
+name, e.g. `<A >+`. In this case, the repetitions have spaces between
+them, e.g. `<A> <A>`.
+
+Production rules are case-sensitive. By convention, terminals start
+with a lowercase letter.
+
+## Example
+
+The following is the term/expression/factor grammar you might
+encounter in a textbook about parsing. However, instead
+of _parsing_ equations, RRR will generate random ones.
+
+(This example is also available as a loadable module in the included
+`term.js` file.)
+
+    ::javascript
+    var grammar = new rrr.Grammar({
+        // Canonical expression/term/factor grammar.
+
+        Expr: ['<Term>', '<Term> + <Term>', '<Term> - <Term>'],
+        Term: ['<Fact>', '<Fact> * <Fact>', '<Fact> / <Fact>'],
+        Sign: ['-', ''],
+
+        // If a parenthesized expression is as likely as a number, the
+        // expansion explodes and overflows the stack. You can prove
+        // this by multiplying out the probabilities: On average, Expr
+        // produces 5/3 Terms, Terms produce 5/3 Facts, and Fact
+        // produces 1/2 Exprs.
+        //
+        // So with equal weights Expr produces, on average,
+        // (5/3)*(5/3)*(1/2) ~= 1.4 Exprs.
+        //
+        // That means Expr must be weighed at _most_ 1/1.4 ~= 0.72
+        // relative to the other option to produce one Expr, and in
+        // practice should be even less to avoid "lucky" stack
+        // overflows.
+        Fact: { '<Number>': 1, '<Sign>(<Expr>)': 0.4 },
+
+        // A numeral may not begin with a 0.
+        Number: ['<Sign><digit><digit0>*'],
+        digit: '123456789',
+        digit0: '1234567890'
+
+    }, '<Expr>'); // This is the default start token.
+    
+To generate a random equation, call `grammar.generate()`. If you want
+a start expression other than the default, you can provide a different
+initial string.
+
+    ::javascript
+    grammar.generate(); // Equivalent to grammar.generate('<Expr>')
+    // => '-9 * 3512 + (-(-51 - -9 / 6) / -6278 + -4 * 30321) / 21940'
+
+    grammar.generate('Solve: <Expr>');
+    // => 'Solve: 7 + (255 * (4 / 18))'
+
+    grammar.generate("Today's numbers are <Number> and <Number>.");
+    // => 'Today\'s numbers are 94 and -142.'
+
+Because RRR is not parsing and unconcerned with ambiguity, some of the
+standard rules could be simplified. For example, `Expr` could be
+written as `<Fact> <op> <Fact>` (with `op` defined as `+-*/`),
+removing the need for `Term`. Such a grammar would still generate only
+valid expressions, but with slightly different probabilities.
+
+## FAQ
+
+### Why doesn't `expand` return?
+### Why do I get `RangeError: Maximum call stack size exceeded`?
+
+Your grammar contains infinitely recursive rules. This is not
+currently handled.
+
+### Why aren't `foo{4}`, `foo+`, etc. working?
+
+Repetition modifiers only apply to rules, not literals.
+
+### Can I use `+` but with a chance other than ½?
+
+If you need probabilities other than 50% you can use weighted rules, e.g.
+
+    { A: { '<foo>": 0.8, "<foo><A>": 0.2 } }
+
+will contain one `<foo>` 80% of the time, two 16% of the time, three
+3.2% of the time, etc.
+
+
+[L-system]: http://en.wikipedia.org/wiki/L-system
+[Markov machine]: http://en.wikipedia.org/wiki/Markov_algorithm
+[stochastic grammar]: http://en.wikipedia.org/wiki/Stochastic_grammar
+[BNF]: http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form

diff --git a/javascript.mk b/javascript.mk
new file mode 100644 (file)
index 0000000..0e6a180
--- /dev/null
+++ b/javascript.mk
@@ -0,0 +1,59 @@
+# This is free and unencumbered software released into the public
+# domain. To the extent possible under law, the author of this file
+# waives all copyright and related or neighboring rights to it.
+
+.DELETE_ON_ERROR:
+
+javascript>fallback = $(firstword $(shell command -v $1) $2 $1)
+
+NPM ?= npm
+NPMROOT ?= .
+
+npmbindir = $(NPMROOT)/node_modules/.bin
+.PRECIOUS: $(npmbindir)/%
+
+from-npm = $(call javascript>fallback,$1,$(npmbindir)/$1)
+
+JSTEST ?= $(npmbindir)/jstest
+JSHINT ?= $(call from-npm,jshint)
+
+uglifyjs_npm_package := uglify-js
+
+UGLIFY ?= $(call from-npm,uglifyjs)
+UGLIFYFLAGS ?= --comments \
+               --compress $(UGLIFYCOMPRESSFLAGS) \
+               --mangle $(UGLIFYMANGLEFLAGS)
+
+JSSTAMPDIR ?= build/stamp
+JSHINTDIR ?= $(JSSTAMPDIR)
+JSTESTDIR ?= $(JSSTAMPDIR)
+JSUGLYDIR ?= .
+
+JSHINTFLAGS += $(if $(JSHINTCONFIG),--config $(JSHINTCONFIG))
+JSTESTFLAGS += $(if $(JSTESTFORMAT),--format $(JSTESTFORMAT))
+JSTESTFORMAT ?= spec
+
+jshint-stampify = $(patsubst %.js,$(JSHINTDIR)/%.js.lint,$1)
+uglify-stampify = $(patsubst %.js,$(JSUGLYDIR)/%.min.js,$1)
+
+javascript>capture-to-target = @echo "$1" && $1 > $@ || (cat $@ && exit 1)
+
+UGLIFY.js = $(UGLIFY) $(UGLIFYFLAGS)
+LINT.js = $(JSHINT) $(JSHINTFLAGS)
+TEST.js = $(JSTEST) $(JSTESTFLAGS)
+
+$(JSUGLYDIR)/%.min.js: %.js | $(UGLIFY)
+       @mkdir -p $(@D)
+       $(UGLIFY.js) < $< > $@
+
+$(JSHINTDIR)/%.js.lint: %.js | $(JSHINT)
+       @mkdir -p $(@D)
+       $(LINT.js) $<
+       @touch $@
+
+$(JSTESTDIR)/%.js.test: %.js $(JSTEST_SOURCES) | $(JSTEST)
+       @mkdir -p $(@D)
+       $(call javascript>capture-to-target,$(TEST.js) $<)
+
+$(npmbindir)/%:
+       $(NPM) install $(firstword $(value $(@F)_npm_package) $(@F))

diff --git a/package.json b/package.json
new file mode 100644 (file)
index 0000000..6842060
--- /dev/null
+++ b/package.json
@@ -0,0 +1,27 @@
+{
+    "name": "rrr",
+    "version": "1.0.0",
+    "author": "Joe Wreschnig",
+    "description": "recursive random rewrites",
+    "keywords": ["random", "text"],
+
+    "license": "GPL-2.0+",
+
+    "main": "./rrr.js",
+
+    "scripts": {
+        "test": "make check"
+    },
+
+    "homepage": "https://yukkurigames.com/rrr",
+    "repository": {
+        "type": "git",
+        "url": "http://git.yukkurigames.com/rrr.git"
+    },
+
+    "devDependencies": {
+        "jstest": "*",
+        "jshint": "*",
+        "uglify-js": "*"
+    }
+}

diff --git a/rrr.js b/rrr.js
new file mode 100644 (file)
index 0000000..2b76474
--- /dev/null
+++ b/rrr.js
@@ -0,0 +1,104 @@
+/* rrr - recursive random rewrites
+   Copyright 2014 Joe Wreschnig
+   Licensed under the terms of the GNU GPL v2 or later
+   @license https://www.gnu.org/licenses/gpl-2.0.html
+   @source: https://yukkurigames.com/rrr/
+*//*
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+   General Public License for more details.
+
+   As additional permission, you may distribute the program or works
+   based on it without the copy of the GNU GPL normally required,
+   provided you include this license notice and a URL through which
+   recipients can access the corresponding source code.
+*/
+
+(function (exports) {
+    "use strict";
+
+    function randfloat (hi) { return Math.random() * hi; }
+    function randint (hi) { return randfloat(hi) | 0; }
+    function randchoice (seq) { return seq[randint(seq.length)]; }
+    function randrange (lo, hi) { return lo + randint(hi - lo); }
+
+    function Productions (dfn) {
+        this.__total = 0;
+        if (Array.isArray(dfn) || dfn.toString() === dfn) {
+            this.__rules = Array.prototype.slice.call(dfn);
+        } else if (typeof dfn === "function") {
+            this.__rules = dfn;
+        } else {
+            this.__rules = {};
+            Object.keys(dfn).forEach(function (key) {
+                var value = dfn[key];
+                this.__total += value;
+                this.__rules[key] = value;
+            }, this);
+        }
+    }
+
+    Productions.prototype.randproduction = function () {
+        if (Array.isArray(this.__rules))
+            return randchoice(this.__rules);
+
+        else if (typeof this.__rules === "function")
+            return this.__rules();
+
+        var x = randfloat(this.__total);
+        for (var k in this.__rules) {
+            x -= this.__rules[k];
+            if (x < 0)
+                return k;
+        }
+        return null;
+    };
+
+    function Grammar (productions, start) {
+        this.start = start || "";
+        this.productions = {};
+        for (var k in productions)
+            this.productions[k] = new Productions(productions[k]);
+    }
+
+    function randcount (lo, hi, rep) {
+        var n = hi ? randrange(+lo, +hi + 1)
+            : lo ? +lo
+            : 1;
+
+        var m = 1;
+        switch (rep) {
+        case '*': m = 0; while (Math.random() < 0.5) ++m; break;
+        case '+': while (Math.random() < 0.5) ++m; break;
+        case '?': m = +(Math.random() < 0.5); break;
+        }
+        return n * m;
+    }
+
+    function repeat (n, f) {
+        var r = [];
+        while (n-- > 0)
+            r.push(f());
+        return r;
+    }
+
+    var R = /<([^> ]+)( ?)>(?:{([0-9]+)(?:,([0-9]+))?}|(\*|\+|\?))?/g;
+    Grammar.prototype.expand = function (start) {
+        var g = this;
+        start = start || this.start;
+        return start.replace(R, function _ (match, p, w, lo, hi, rep) {
+            var prod = g.productions[p];
+            return repeat(randcount(lo, hi, rep), function () {
+                return prod.randproduction().replace(R, _);
+            }).join(w);
+        });
+    };
+
+    exports.Grammar = Grammar;
+})(typeof module !== "undefined" ? module.exports : this.gengram = {});

diff --git a/term.js b/term.js
new file mode 100644 (file)
index 0000000..b779f8c
--- /dev/null
+++ b/term.js
@@ -0,0 +1,33 @@
+(function (exports) {
+    /*global require */
+    var rrr = exports.rrr || require('./rrr');
+
+    var grammar = new rrr.Grammar({
+        // Canonical expression/term/factor grammar.
+        Expr: ['<Term>', '<Term> + <Term>', '<Term> - <Term>'],
+        Term: ['<Fact>', '<Fact> * <Fact>', '<Fact> / <Fact>'],
+        Sign: ['-', ''],
+
+        // If a parenthesized expression is as likely as a number, the
+        // expansion explodes and overflows the stack. You can prove
+        // this by multiplying out the probabilities: On average, Expr
+        // produces 5/3 Terms, Terms produce 5/3 Facts, and Fact
+        // produces 1/2 Exprs.
+        //
+        // So with equal weights Expr produces, on average,
+        // (5/3)*(5/3)*(1/2) ~= 1.4 Exprs.
+        //
+        // That means Expr must be weighed at _most_ 1/1.4 ~= 0.72
+        // relative to the other option to produce one Expr, and in
+        // practice should be even less to avoid "lucky" stack
+        // overflows.
+        Fact: { '<Number>': 1, '<Sign>(<Expr>)': 0.4 },
+
+        // A numeral may not begin with a 0.
+        Number: ['<Sign><digit><digit0>*'],
+        digit: '123456789',
+        digit0: '1234567890'
+    }, '<Expr>');
+
+    exports.randomEquation = grammar.expand.bind(grammar);
+})(typeof module !== 'undefined' ? module.exports : this);

diff --git a/tests/jshint.config b/tests/jshint.config
new file mode 100644 (file)
index 0000000..fdc8a7d
--- /dev/null
+++ b/tests/jshint.config
@@ -0,0 +1,13 @@
+{
+    "camelcase": true,
+    "eqeqeq": true,
+    "indent": 4,
+    "latedef": true,
+    "nonew": true,
+    "trailing": true,
+    "undef": true,
+    "evil": true,
+    "globals": {
+        "module": false
+    }
+}

diff --git a/tests/rrr.js b/tests/rrr.js
new file mode 100644 (file)
index 0000000..679e055
--- /dev/null
+++ b/tests/rrr.js
@@ -0,0 +1,68 @@
+/*global require, it, assert, assertEqual, assertNot */
+/*jshint -W085 */ // "Don't use 'with'."
+
+var JS = this.JS || require('jstest');
+var rrr = require('../rrr');
+
+var AB = new rrr.Grammar({
+    A: ["A"],
+    B: ["B"],
+    AB: ["<A> <B>"],
+}, "<AB >+");
+
+var DIGITS = new rrr.Grammar({
+    Digits: ["<digit>+"],
+    digit: "0123456789"
+});
+
+JS.Test.describe('rrr AB', function () { with (this) {
+    it("simply expands", function () { with (this) {
+        assertEqual("A", AB.expand("<A>"));
+        assertEqual("B", AB.expand("<B>"));
+        assertEqual("A B", AB.expand("<AB>"));
+    }});
+    it("expands multiple tokens", function () { with (this) {
+        assertEqual("A B A", AB.expand("<A> <B> <A>"));
+    }});
+    it("expands multiple times", function () { with (this) {
+        assertEqual("AAAAA", AB.expand("<A>{5}"));
+    }});
+    it("expands random times", function () { with (this) {
+        var r = [];
+        for (var i = 0; i < 1000; ++i)
+            r.push(AB.expand("<A>{1,10}"));
+        assert(r.indexOf("") < 0);
+        assert(r.indexOf("A") >= 0);
+        assert(r.indexOf("AA") >= 0);
+        assert(r.indexOf("AAA") >= 0);
+        assert(r.indexOf("AAAA") >= 0);
+        assert(r.indexOf("AAAAA") >= 0);
+        assert(r.indexOf("AAAAAA") >= 0);
+        assert(r.indexOf("AAAAAAA") >= 0);
+        assert(r.indexOf("AAAAAAAA") >= 0);
+        assert(r.indexOf("AAAAAAAAA") >= 0);
+        assert(r.indexOf("AAAAAAAAAA") >= 0);
+        assert(r.indexOf("AAAAAAAAAAA") < 0);
+    }});
+    it("expands repeatedly", function () { with (this) {
+        var r = [];
+        for (var i = 0; i < 100; ++i)
+            r.push(AB.expand());
+        assert(r.indexOf("") < 0);
+        assert(r.indexOf("A B") >= 0);
+        assert(r.indexOf("A B A B") >= 0);
+    }});
+    it("expands repetitions differently", function () { with (this) {
+        var r = DIGITS.expand("<digit>{500}");
+        assert(~r.indexOf("0"));
+        assert(~r.indexOf("1"));
+        assert(~r.indexOf("2"));
+        assert(~r.indexOf("3"));
+        assert(~r.indexOf("4"));
+        assert(~r.indexOf("5"));
+        assert(~r.indexOf("6"));
+        assert(~r.indexOf("7"));
+        assert(~r.indexOf("8"));
+        assert(~r.indexOf("9"));
+    }});
+}});

diff --git a/tests/term.js b/tests/term.js
new file mode 100644 (file)
index 0000000..732fa5a
--- /dev/null
+++ b/tests/term.js
@@ -0,0 +1,15 @@
+/*global require, it, assert, assertEqual, assertNot */
+/*jshint -W085 */ // "Don't use 'with'."
+
+var JS = this.JS || require('jstest');
+var rrr = require('../rrr');
+var term = require('../term');
+
+JS.Test.describe('rrr term test', function () { with (this) {
+    it("loads and makes expressions", function () { with (this) {
+        for (var i = 0; i < 1000; ++i) {
+            var n = eval(term.randomEquation());
+            assert(n === +n);
+        }
+    }});
+}});