From e0b476cc0afaaa1ddf97dbb518b0860d5f01a370 Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Thu, 24 Jul 2014 20:18:51 -0700
Subject: [PATCH] matchPattern, projectObjects

---
 src/route.js | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
 test/tr.js   | 40 +++++++++++++++++++++-------------------
 2 files changed, 67 insertions(+), 20 deletions(-)

diff --git a/src/route.js b/src/route.js
index 28cf361..79a1cd4 100644
--- a/src/route.js
+++ b/src/route.js
@@ -145,6 +145,45 @@ function compilePattern(v, p) {
     }
 }
 
+function matchPattern(v, p) {
+    var captureCount = 0;
+    var result = {};
+    try {
+	walk(v, p);
+    } catch (e) {
+	if (e.matchPatternFailed) return null;
+	throw e;
+    }
+    result.length = captureCount;
+    return result;
+
+    function walk(v, p) {
+	if (p === v) return;
+
+	if (p === __) return;
+
+	if (Array.isArray(p) && Array.isArray(v) && p.length === v.length) {
+	    for (var i = 0; i < p.length; i++) {
+		walk(v[i], p[i]);
+	    }
+	    return;
+	}
+
+	if (isCapture(p)) {
+	    var thisCapture = captureCount++;
+	    walk(v, capturePattern(p));
+	    result[captureName(p) || ('$' + thisCapture)] = v;
+	    return;
+	}
+
+	if (p instanceof $Embedded) {
+	    die("$Embedded patterns not supported in matchPattern()");
+	}
+
+	throw {matchPatternFailed: true};
+    }
+}
+
 function shallowCopyArray(s) {
     return s.slice();
 }
@@ -1044,13 +1083,17 @@ function matcherKeysToObjects(matcherKeysResult, compiledProjection) {
 	var e = matcherKeysResult[i];
 	var d = {};
 	for (var j = 0; j < e.length; j++) {
-	    d[compiledProjection.names[j] || j] = e[j];
+	    d[compiledProjection.names[j] || ('$' + j)] = e[j];
 	}
 	result.push(d);
     }
     return result;
 }
 
+function projectObjects(m, compiledProjection) {
+    return matcherKeysToObjects(matcherKeys(project(m, compiledProjection)), compiledProjection);
+}
+
 function prettyMatcher(m, initialIndent) {
     var acc = [];
     walk(initialIndent || 0, m);
@@ -1514,6 +1557,7 @@ module.exports.is_emptyMatcher = is_emptyMatcher;
 module.exports.emptyMatcher = emptyMatcher;
 module.exports.embeddedMatcher = embeddedMatcher;
 module.exports.compilePattern = compilePattern;
+module.exports.matchPattern = matchPattern;
 module.exports.union = unionN;
 module.exports.intersect = intersect;
 module.exports.erasePath = erasePath;
@@ -1526,6 +1570,7 @@ module.exports.projectionToPattern = projectionToPattern;
 module.exports.project = project;
 module.exports.matcherKeys = matcherKeys;
 module.exports.matcherKeysToObjects = matcherKeysToObjects;
+module.exports.projectObjects = projectObjects;
 module.exports.matcherEquals = matcherEquals;
 module.exports.prettyMatcher = prettyMatcher;
 module.exports.serializeMatcher = serializeMatcher;
diff --git a/test/tr.js b/test/tr.js
index 2818732..a3756c6 100644
--- a/test/tr.js
+++ b/test/tr.js
@@ -205,8 +205,8 @@ dumpM(r.union(r.compilePattern(r.arrayToSet('A'), [2]),
     var M2 = r.project(M, proj);
     dump(r.matcherKeys(M2));
     dump(r.matcherKeys(r.project(M2, r.compileProjection(r._$, r._$))));
-    dump(r.matcherKeysToObjects(r.matcherKeys(r.project(M2, r.compileProjection(r._$, r._$))),
-				proj));
+    dump(r.matcherKeysToObjects(r.matcherKeys(M2), proj));
+    dump(r.projectObjects(M, proj));
 })();
 
 (function () {
@@ -214,23 +214,9 @@ dumpM(r.union(r.compilePattern(r.arrayToSet('A'), [2]),
     var M = r.union(r.compilePattern(r.arrayToSet(['A']), [1, 2]),
 		    r.compilePattern(r.arrayToSet(['C']), [1, 3]),
 		    r.compilePattern(r.arrayToSet(['B']), [3, 4]));
-    var proj = r.compileProjection([r._$("fst"), r._$("snd")]);
-    var M2 = r.project(M, proj);
-    dump(r.matcherKeys(M2));
-    dump(r.matcherKeysToObjects(r.matcherKeys(r.project(M2, r.compileProjection(r._$, r._$))),
-				proj));
-})();
-
-(function () {
-    console.log("matcherKeys using multiple-values in projections, with partial names");
-    var M = r.union(r.compilePattern(r.arrayToSet(['A']), [1, 2]),
-		    r.compilePattern(r.arrayToSet(['C']), [1, 3]),
-		    r.compilePattern(r.arrayToSet(['B']), [3, 4]));
-    var proj = r.compileProjection([r._$, r._$("snd")]);
-    var M2 = r.project(M, proj);
-    dump(r.matcherKeys(M2));
-    dump(r.matcherKeysToObjects(r.matcherKeys(r.project(M2, r.compileProjection(r._$, r._$))),
-				proj));
+    dump(r.projectObjects(M, r.compileProjection([r._$("fst"), r._$("snd")])));
+    dump(r.projectObjects(M, r.compileProjection([r._$, r._$("snd")])));
+    dump(r.projectObjects(M, r.compileProjection([r._$("fst"), r._$])));
 })();
 
 (function () {
@@ -289,3 +275,19 @@ dumpM(r.union(r.compilePattern(r.arrayToSet('A'), [2]),
     dump(r.matcherEquals(M1a, M1b) === true);
     dump(r.matcherEquals(M2a, M2b) === true);
 })();
+
+(function () {
+    console.log("Calls to matchPattern");
+    dump(r.matchPattern([1, 2, 3], [r.__, 2, r._$]));
+    dump(r.matchPattern([1, 2, 3], [r.__, 2, r._$("three")]));
+    dump(r.matchPattern([1, 2, 3], [r._$, 2, r._$("three")]));
+    dump(r.matchPattern([1, 2, 3], [r._$("one"), 2, r._$]));
+    dump(r.matchPattern([1, 2, 3], [r._$("one"), 2, r._$("three")]));
+    dump(r.matchPattern([1, 2, 3], [r.__, 999, r._$("three")]) === null);
+    dump(r.matchPattern([1, 2, 3], [r.__, 2, r._$("three"), 4]) === null);
+
+    dump(r.matchPattern([1, [2, 999], 3], [r._$("one"), r._$(null, [2, r.__]), r._$("three")]));
+    dump(r.matchPattern([1, [2, 999], 3], [r._$("one"), r._$("two", [2, r.__]), r._$("three")]));
+    dump(r.matchPattern([1, [2, 999], 3], [r._$("one"), r._$(null, [2, r._$]), r._$("three")]));
+    dump(r.matchPattern([1, [2, 999], 3], [r._$("one"), r._$("two", [2, r._$]), r._$("three")]));
+})();