From c90a75823053f1c1ef33c675d42037aa386a88c0 Mon Sep 17 00:00:00 2001
From: John Foerch <jjfoerch@earthlink.net>
Date: Sun, 2 Dec 2012 09:40:23 -0500
Subject: [PATCH] position_in_strings: new util

Planned usage in future completer nesting design.
---
 modules/string.js     | 21 +++++++++++++++++
 tests/simple/utils.js | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/modules/string.js b/modules/string.js
index 13cf984..4331c5a 100644
--- a/modules/string.js
+++ b/modules/string.js
@@ -175,4 +175,25 @@ function build_url_regexp () {
 }
 
 
+/**
+ * position_in_strings takes a position and an array of strings, and
+ * returns the index of the string in the array that the position is in.
+ * At any position which is on the boundary between two strings, the lower
+ * string is the one that the position is considered to be in.  This
+ * counts also for the first string, so a position of 0 always returns the
+ * index -1, that is, "before the first string".
+ */
+function position_in_strings (strings, pos) {
+    for (var i = 0, t = 0, n = strings.length;
+         i < n;
+         ++i)
+    {
+        if (strings[i] == null || pos <= t)
+            break;
+        t += strings[i].length;
+    }
+    return i - 1;
+}
+
+
 provide("string");
diff --git a/tests/simple/utils.js b/tests/simple/utils.js
index 4d2e9ea..89fe7bb 100644
--- a/tests/simple/utils.js
+++ b/tests/simple/utils.js
@@ -46,6 +46,7 @@ walnut_run({
     }
 });
 
+
 walnut_run({
     test_possibly_valid_url_1: function () {
         assert_not(possibly_valid_url(""));
@@ -81,3 +82,64 @@ walnut_run({
         assert(possibly_valid_url("/"));
     }
 });
+
+
+walnut_run({
+    test_position_in_strings_1: function () {
+        assert_equals(position_in_strings([null], 0), -1);
+    },
+    test_position_in_strings_2: function () {
+        assert_equals(position_in_strings([], 0), -1);
+    },
+    test_position_in_strings_3: function () {
+        assert_equals(position_in_strings(["a"], 0), -1);
+    },
+    test_position_in_strings_4: function () {
+        assert_equals(position_in_strings(["a"], 1), 0);
+    },
+    test_position_in_strings_5: function () {
+        assert_equals(position_in_strings(["a"], 2), 0);
+    },
+    test_position_in_strings_6: function () {
+        assert_equals(position_in_strings(["a", "b"], 1), 0);
+    },
+    test_position_in_strings_7: function () {
+        assert_equals(position_in_strings(["a", "b"], 2), 1);
+    },
+    test_position_in_strings_8: function () {
+        assert_equals(position_in_strings(["a", "b"], 3), 1);
+    },
+    test_position_in_strings_9: function () {
+        assert_equals(position_in_strings(["a", "b", "c"], 3), 2);
+    },
+    test_position_in_strings_10: function () {
+        assert_equals(position_in_strings([""], 1), 0);
+    },
+    test_position_in_strings_11: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 0), -1);
+    },
+    test_position_in_strings_12: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 1), 0);
+    },
+    test_position_in_strings_13: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 2), 0);
+    },
+    test_position_in_strings_14: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 3), 0);
+    },
+    test_position_in_strings_15: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 4), 1);
+    },
+    test_position_in_strings_16: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 5), 2);
+    },
+    test_position_in_strings_17: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 6), 2);
+    },
+    test_position_in_strings_18: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 7), 2);
+    },
+    test_position_in_strings_19: function () {
+        assert_equals(position_in_strings(["foo", " ", "bar"], 8), 2);
+    }
+});
-- 
2.11.4.GIT