Merge pull request #79 from michaelficarra/codepoints

add codepoint-based string functions as Data.String.CodePoints

Author: hdgarrood

bower.json

@@ -20,7 +20,9 @@
     "purescript-either": "^3.0.0",
     "purescript-gen": "^1.1.0",
     "purescript-maybe": "^3.0.0",
-    "purescript-partial": "^1.2.0"
+    "purescript-partial": "^1.2.0",
+    "purescript-unfoldable": "^3.0.0",
+    "purescript-arrays": "^4.0.1"
   },
   "devDependencies": {
     "purescript-assert": "^3.0.0",

src/Data/String/CodePoints.js

@@ -0,0 +1,108 @@
+"use strict";
+/* global Symbol */
+
+var hasArrayFrom = typeof Array.from === "function";
+var hasStringIterator =
+  typeof Symbol !== "undefined" &&
+  Symbol != null &&
+  typeof Symbol.iterator !== "undefined" &&
+  typeof String.prototype[Symbol.iterator] === "function";
+var hasFromCodePoint = typeof String.prototype.fromCodePoint === "function";
+var hasCodePointAt = typeof String.prototype.codePointAt === "function";
+
+exports._unsafeCodePointAt0 = function (fallback) {
+  return hasCodePointAt
+    ? function (str) { return str.codePointAt(0); }
+    : fallback;
+};
+
+exports._codePointAt = function (fallback) {
+  return function (Just) {
+    return function (Nothing) {
+      return function (unsafeCodePointAt0) {
+        return function (index) {
+          return function (str) {
+            var length = str.length;
+            if (index < 0 || index >= length) return Nothing;
+            if (hasStringIterator) {
+              var iter = str[Symbol.iterator]();
+              for (var i = index;; --i) {
+                var o = iter.next();
+                if (o.done) return Nothing;
+                if (i === 0) return Just(unsafeCodePointAt0(o.value));
+              }
+            }
+            return fallback(index)(str);
+          };
+        };
+      };
+    };
+  };
+};
+
+exports._count = function (fallback) {
+  return function (unsafeCodePointAt0) {
+    if (hasStringIterator) {
+      return function (pred) {
+        return function (str) {
+          var iter = str[Symbol.iterator]();
+          for (var cpCount = 0; ; ++cpCount) {
+            var o = iter.next();
+            if (o.done) return cpCount;
+            var cp = unsafeCodePointAt0(o.value);
+            if (!pred(cp)) return cpCount;
+          }
+        };
+      };
+    }
+    return fallback;
+  };
+};
+
+exports._fromCodePointArray = function (singleton) {
+  return hasFromCodePoint
+    ? function (cps) {
+      // Function.prototype.apply will fail for very large second parameters,
+      // so we don't use it for arrays with 10,000 or more entries.
+      if (cps.length < 10e3) {
+        return String.fromCodePoint.apply(String, cps);
+      }
+      return cps.map(singleton).join("");
+    }
+    : function (cps) {
+      return cps.map(singleton).join("");
+    };
+};
+
+exports._singleton = function (fallback) {
+  return hasFromCodePoint ? String.fromCodePoint : fallback;
+};
+
+exports._take = function (fallback) {
+  return function (n) {
+    if (hasStringIterator) {
+      return function (str) {
+        var accum = "";
+        var iter = str[Symbol.iterator]();
+        for (var i = 0; i < n; ++i) {
+          var o = iter.next();
+          if (o.done) return accum;
+          accum += o.value;
+        }
+        return accum;
+      };
+    }
+    return fallback(n);
+  };
+};
+
+exports._toCodePointArray = function (fallback) {
+  return function (unsafeCodePointAt0) {
+    if (hasArrayFrom) {
+      return function (str) {
+        return Array.from(str, unsafeCodePointAt0);
+      };
+    }
+    return fallback;
+  };
+};