add bsearch

docs/lib2x-bsearch.md

@@ -1,25 +0,0 @@
-# bsearch
-
-The `bsearch` function is a general-purpose function to find a value or a list of values in a vector. The vector must be sorted by zyx (from the last index to the first one).
-
-**Since:**  2.3
-
-## Parameters
-
-- `sorted` : The sorted vector.
-- `elem` : a list of values.
-- `by` : Can be `"x"`、`"y"`、`"z"`, `"idx"` (Default) or `"vt"`. 
-- `idx` : When `by` is `"idx"`, the value of `idx` is used. The Default value is 0.
-
-## Examples
-
-	use <util/sort.scad>;
-	use <util/bsearch.scad>;
-
-	points = [[1, 1], [3, 4], [7, 2], [5, 2]];
-	sorted = sort(points, by = "vt");
-
-	echo(sorted); //  [[1, 1], [5, 2], [7, 2], [3, 4]]
-	assert(bsearch(sorted, [5, 4], by = "x") == 1);   
-	assert(bsearch(sorted, [5, 4], by = "y") == 3);   
-	assert(bsearch(sorted, [7, 2], by = "vt") == 2);

docs/lib3x-bsearch.md

@@ -0,0 +1,26 @@
+# bsearch
+
+The `bsearch` function is a general-purpose function to search a value in a list whose elements must be sorted by zyx (from the last index to the first one).
+
+**Since:**  3.0
+
+## Parameters
+
+- `sorted` : The sorted list.
+- `target` : The target vector or a function literal. 
+
+## Examples
+
+	use <util/sort.scad>;
+	use <util/bsearch.scad>;
+
+    points = [[1, 1], [3, 4], [7, 2], [5, 2]];
+    sorted = sort(points, by = "vt"); //  [[1, 1], [5, 2], [7, 2], [3, 4]]
+
+    assert(bsearch(sorted, [7, 2]) == 2);
+
+    xIs5 = function(elem) elem[0] - 5;
+    assert(bsearch(sorted, xIs5) == 1);
+
+    yIs4 = function(elem) elem[1] - 4;
+    assert(bsearch(sorted, yIs4) == 3);

src/util/_impl/_bsearch_impl.scad

@@ -1,20 +1,13 @@
 use <_vt_default_comparator.scad>;
 
-function _binary_search_by(sorted, elem, low, upper, i) =
-    low > upper ? -1 :
-    let(mid = floor((low + upper) / 2))
-    sorted[mid][i] < elem[i] ? _binary_search_by(sorted, elem, mid + 1, upper, i) :
-    sorted[mid][i] > elem[i] ? _binary_search_by(sorted, elem, low, mid - 1, i) : mid;
-
 function _bsearch_vt(sorted, elem, low, upper) =
     low > upper ? -1 :
     let(mid = floor((low + upper) / 2))
     lessThan(sorted[mid], elem) ? _bsearch_vt(sorted, elem, mid + 1, upper) :
     greaterThan(sorted[mid], elem) ? _bsearch_vt(sorted, elem, low, mid - 1) : mid;
 
-function _bsearch_by(sorted, elem, by, idx) =
-    let(
-        dict = [["x", 0], ["y", 1], ["z", 2], ["i", idx]],
-        i = dict[search(by == "idx" ? "i" : by, dict)[0]][1]
-    )
-    _binary_search_by(sorted, elem, 0, len(sorted) - 1, i);
+function _bsearch_cmp(sorted, cmp, low, upper) =
+    low > upper ? -1 :
+    let(mid = floor((low + upper) / 2))
+    cmp(sorted[mid]) < 0 ? _bsearch_cmp(sorted, cmp, mid + 1, upper) :
+    cmp(sorted[mid]) > 0 ? _bsearch_cmp(sorted, cmp, low, mid - 1) : mid;

src/util/bsearch.scad

@@ -4,12 +4,12 @@
 * @copyright Justin Lin, 2020
 * @license https://opensource.org/licenses/lgpl-3.0.html
 *
-* @see https://openhome.cc/eGossip/OpenSCAD/lib2x-bsearch.html
+* @see https://openhome.cc/eGossip/OpenSCAD/lib3x-bsearch.html
 *
 **/
 
 use <_impl/_bsearch_impl.scad>;
 
-function bsearch(sorted, elem, by = "idx", idx = 0) = 
-    by == "vt" ? _bsearch_vt(sorted, elem, 0, len(sorted) - 1) : // for example, `sorted` is by zyx
-                 _bsearch_by(sorted, elem, by, idx);
+function bsearch(sorted, target) = 
+    is_function(target) ? _bsearch_cmp(sorted, target, 0, len(sorted) - 1) :
+                          _bsearch_vt(sorted, target, 0, len(sorted) - 1); // `sorted` is by zyx

test/util/test_bsearch.scad

@@ -0,0 +1,19 @@
+use <util/sort.scad>;
+use <util/bsearch.scad>;
+
+module test_bsearch() {
+    echo("==== test_bsearch ====");
+
+    points = [[1, 1], [3, 4], [7, 2], [5, 2]];
+    sorted = sort(points, by = "vt"); //  [[1, 1], [5, 2], [7, 2], [3, 4]]
+
+    assert(bsearch(sorted, [7, 2]) == 2);
+
+    xIs5 = function(elem) elem[0] - 5;
+    assert(bsearch(sorted, xIs5) == 1);
+
+    yIs4 = function(elem) elem[1] - 4;
+    assert(bsearch(sorted, yIs4) == 3);
+}
+
+test_bsearch();