CMaps binary packing

external/cmapscompress/optimize.js

@@ -0,0 +1,211 @@
+/* Copyright 2014 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+exports.optimizeCMap = function (data) {
+  var i = 1;
+  while (i < data.body.length) {
+    if (data.body[i - 1].type === data.body[i].type) {
+      data.body[i - 1].items = data.body[i - 1].items.concat(data.body[i].items);
+      data.body.splice(i, 1);
+    } else {
+      i++;
+    }
+  }
+  // split into groups with different lengths
+  var i = 0;
+  while (i < data.body.length) {
+    var item = data.body[i];
+    var keys = Object.keys(item.items[0]).filter(function (i) {
+      return typeof item.items[0][i] === 'string';
+    });
+    var j = 1;
+    while (j < item.items.length) {
+      var different = false;
+      for (var q = 0; q < keys.length && !different; q++) {
+        different = item.items[j - 1][keys[q]].length !== item.items[j][keys[q]].length;
+      }
+      if (different) {
+        break;
+      }
+      j++;
+    }
+    if (j < item.items.length) {
+      data.body.splice(i + 1, 0, {
+        type: item.type,
+        items: item.items.splice(j, item.items.length - j)
+      });
+    }
+    i++;
+  }
+  // find sequences of single char ranges
+  var i = 0;
+  while (i < data.body.length) {
+    var item = data.body[i];
+    if (item.type === 3 || item.type === 5) {
+      var j = 0;
+      while (j < item.items.length) {
+        var q = j;
+        while (j < item.items.length && item.items[j].start === item.items[j].end) {
+          j++;
+        }
+        if ((j - q) >= 9) {
+          if (j < item.items.length) {
+            data.body.splice(i + 1, 0, {
+              type: item.type,
+              items: item.items.splice(j, item.items.length - j)
+            });
+          }
+          if (q > 0) {
+            data.body.splice(i + 1, 0, {
+              type: item.type - 1,
+              items: item.items.splice(q, j - q).map(function (i) {
+                return {char: i.start, code: i.code };
+              })
+            });
+            i++;
+          } else {
+            item.type -= 1;
+            item.items = item.items.map(function (i) {
+              return {char: i.start, code: i.code };
+            });
+          }
+          continue;
+        }
+        j++;
+      }
+    }
+    i++;
+  }
+
+  //  find sequences of increasing code/ranges order
+  var i = 0;
+  while (i < data.body.length) {
+    var item = data.body[i];
+    if (item.type >= 2 && item.type <= 5) {
+      var j = 1;
+      var startProp = item.type === 2 || item.type === 4 ? 'char' : 'start';
+      var endProp = item.type === 2 || item.type === 4 ? 'char' : 'end';
+      while (j < item.items.length) {
+        var q = j - 1;
+        while (j < item.items.length && incHex(item.items[j - 1][endProp]) === item.items[j][startProp]) {
+          j++;
+        }
+        if ((j - q) >= 9) {
+          if (j < item.items.length) {
+            data.body.splice(i + 1, 0, {
+              type: item.type,
+              items: item.items.splice(j, item.items.length - j)
+            });
+          }
+          if (q > 0) {
+            data.body.splice(i + 1, 0, {
+              type: item.type,
+              items: item.items.splice(q, j - q),
+              sequence: true
+            });
+            i++;
+          } else {
+            item.sequence = true;
+          }
+          continue;
+        }
+        j++;
+      }
+    }
+    i++;
+  }
+
+  // split non-sequences two groups where codes are close
+  var i = 0;
+  while (i < data.body.length) {
+    var item = data.body[i];
+    if (!item.sequence && (item.type === 2 || item.type === 3)) {
+      var subitems = item.items;
+      var codes = subitems.map(function (i) {
+        return i.code;
+      });
+      codes.sort(function (a, b) {
+        return a - b;
+      });
+      var maxDistance = 100, minItems = 10, itemsPerBucket = 50;
+      if (subitems.length > minItems && codes[codes.length - 1] - codes[0] > maxDistance) {
+        var gapsCount = Math.max(2, (subitems.length / itemsPerBucket) | 0);
+        var gaps = [];
+        for (var q = 0; q < gapsCount; q++) {
+          gaps.push({length: 0});
+        }
+        for (var j = 1; j < codes.length; j++) {
+          var gapLength = codes[j] - codes[j - 1];
+          var q = 0;
+          while (q < gaps.length && gaps[q].length > gapLength) {
+            q++;
+          }
+          if (q >= gaps.length) {
+            continue;
+          }
+          var q0 = q;
+          while (q < gaps.length) {
+            if (gaps[q].length < gaps[q0].length) {
+              q0 = q;
+            }
+            q++;
+          }
+          gaps[q0] = {length: gapLength, boundary: codes[j]};
+        }
+        var groups = gaps.filter(function (g) {
+          return g.length >= maxDistance;
+        }).map(function (g) {
+            return g.boundary;
+          });
+        groups.sort(function (a, b) {
+          return a - b;
+        });
+        if (groups.length > 1) {
+          var buckets = [item.items = []];
+          for (var j = 0; j < groups.length; j++) {
+            var newItem = {type: item.type, items: []}
+            buckets.push(newItem.items);
+            i++;
+            data.body.splice(i, 0, newItem);
+          }
+          for (var j = 0; j < subitems.length; j++) {
+            var code = subitems[j].code;
+            var q = 0;
+            while (q < groups.length && groups[q] <= code) {
+              q++;
+            }
+            buckets[q].push(subitems[j]);
+          }
+        }
+      }
+    }
+    i++;
+  }
+};
+
+function incHex(a) {
+  var c = 1, s = '';
+  for (var i = a.length - 1; i >= 0; i--) {
+    c += parseInt(a[i], 16);
+    if (c >= 16) {
+      s = '0' + s;
+      c = 1;
+    } else {
+      s = c.toString(16) + s;
+      c = 0;
+    }
+  }
+  return s;
+}