Break distance iterator out into separate module

kpdecker · kpdecker · commit 048e7f726a6b · 2015-10-29T01:23:39.000-05:00
diff --git a/src/patch/apply.js b/src/patch/apply.js
@@ -1,4 +1,5 @@
 import {parsePatch} from './parse';
+import distanceIterator from '../util/distance-iterator';
 
 export function applyPatch(source, uniDiff, options = {}) {
   if (typeof uniDiff === 'string') {
@@ -51,49 +52,6 @@ export function applyPatch(source, uniDiff, options = {}) {
     return true;
   }
 
-  function distanceIterator(toPos, minLine, maxLine) {
-    let wantForward = true,
-        backwardExhausted = false,
-        forwardExhausted = false,
-        localOffset = 1;
-
-    return function iterator() {
-      if (wantForward && !forwardExhausted) {
-        if (backwardExhausted) {
-          localOffset++;
-        } else {
-          wantForward = false;
-        }
-
-        // Check if trying to fit beyond text length, and if not, check it fits
-        // after offset location (or desired location on first iteration)
-        if (toPos + localOffset <= maxLine) {
-          return localOffset;
-        }
-
-        forwardExhausted = true;
-      }
-
-      if (!backwardExhausted) {
-        if (!forwardExhausted) {
-          wantForward = true;
-        }
-
-        // Check if trying to fit before text beginning, and if not, check it fits
-        // before offset location
-        if (minLine <= toPos - localOffset) {
-          return -localOffset++;
-        }
-
-        backwardExhausted = true;
-        return iterator();
-      }
-
-      // We tried to fit hunk before text beginning and beyond text lenght, then
-      // hunk can't fit on the text. Return undefined
-    };
-  }
-
   // Search best fit offsets for each hunk based on the previous ones
   for (let i = 0; i < hunks.length; i++) {
     let hunk = hunks[i],
diff --git a/src/util/distance-iterator.js b/src/util/distance-iterator.js
@@ -0,0 +1,45 @@
+// Iterator that traverses in the range of [min, max], stepping
+// by distance from a given start position. I.e. for [0, 4], with
+// start of 2, this will iterate 2, 3, 1, 4, 0.
+export default function(start, minLine, maxLine) {
+  let wantForward = true,
+      backwardExhausted = false,
+      forwardExhausted = false,
+      localOffset = 1;
+
+  return function iterator() {
+    if (wantForward && !forwardExhausted) {
+      if (backwardExhausted) {
+        localOffset++;
+      } else {
+        wantForward = false;
+      }
+
+      // Check if trying to fit beyond text length, and if not, check it fits
+      // after offset location (or desired location on first iteration)
+      if (start + localOffset <= maxLine) {
+        return localOffset;
+      }
+
+      forwardExhausted = true;
+    }
+
+    if (!backwardExhausted) {
+      if (!forwardExhausted) {
+        wantForward = true;
+      }
+
+      // Check if trying to fit before text beginning, and if not, check it fits
+      // before offset location
+      if (minLine <= start - localOffset) {
+        return -localOffset++;
+      }
+
+      backwardExhausted = true;
+      return iterator();
+    }
+
+    // We tried to fit hunk before text beginning and beyond text lenght, then
+    // hunk can't fit on the text. Return undefined
+  };
+}
