diff: function()

in pytheas-core/src/main/resources/js/diff.js [45:109]
51 lines of code
20 McCabe index (conditional complexity)

      diff: function(oldString, newString) {
        // Handle the identity case (this is due to unrolling editLength == 0
        if (newString == oldString) {
          return [{ value: newString }];
        }
        if (!newString) {
          return [{ value: oldString, removed: true }];
        }
        if (!oldString) {
          return [{ value: newString, added: true }];
        }

        newString = this.tokenize(newString);
        oldString = this.tokenize(oldString);

        var newLen = newString.length, oldLen = oldString.length;
        var maxEditLength = newLen + oldLen;
        var bestPath = [{ newPos: -1, components: [] }];

        // Seed editLength = 0
        var oldPos = this.extractCommon(bestPath[0], newString, oldString, 0);
        if (bestPath[0].newPos+1 >= newLen && oldPos+1 >= oldLen) {
          return bestPath[0].components;
        }

        for (var editLength = 1; editLength <= maxEditLength; editLength++) {
          for (var diagonalPath = -1*editLength; diagonalPath <= editLength; diagonalPath+=2) {
            var basePath;
            var addPath = bestPath[diagonalPath-1],
                removePath = bestPath[diagonalPath+1];
            oldPos = (removePath ? removePath.newPos : 0) - diagonalPath;
            if (addPath) {
              // No one else is going to attempt to use this value, clear it
              bestPath[diagonalPath-1] = undefined;
            }

            var canAdd = addPath && addPath.newPos+1 < newLen;
            var canRemove = removePath && 0 <= oldPos && oldPos < oldLen;
            if (!canAdd && !canRemove) {
              bestPath[diagonalPath] = undefined;
              continue;
            }

            // Select the diagonal that we want to branch from. We select the prior
            // path whose position in the new string is the farthest from the origin
            // and does not pass the bounds of the diff graph
            if (!canAdd || (canRemove && addPath.newPos < removePath.newPos)) {
              basePath = clonePath(removePath);
              this.pushComponent(basePath.components, oldString[oldPos], undefined, true);
            } else {
              basePath = clonePath(addPath);
              basePath.newPos++;
              this.pushComponent(basePath.components, newString[basePath.newPos], true, undefined);
            }

            var oldPos = this.extractCommon(basePath, newString, oldString, diagonalPath);

            if (basePath.newPos+1 >= newLen && oldPos+1 >= oldLen) {
              return basePath.components;
            } else {
              bestPath[diagonalPath] = basePath;
            }
          }
        }
      },