Text scanning update (#507)

* Fix unity test missing a parameter

* Update docSentenceExtract to not rescan content

2 files changed, 8 insertions, 4 deletions

diff --git a/ext/fg/js/document.js b/ext/fg/js/document.js
index 6103c7c5..d639bc86 100644
--- a/ext/fg/js/document.js
+++ b/ext/fg/js/document.js
@@ -159,7 +159,7 @@ function docSentenceExtract(source, extent) {
 
     const sourceLocal = source.clone();
     const position = sourceLocal.setStartOffset(extent);
-    sourceLocal.setEndOffset(position + extent);
+    sourceLocal.setEndOffset(extent * 2 - position, true);
     const content = sourceLocal.text();
 
     let quoteStack = [];
diff --git a/ext/fg/js/source.js b/ext/fg/js/source.js
index b3119d40..c9d70215 100644
--- a/ext/fg/js/source.js
+++ b/ext/fg/js/source.js
@@ -46,10 +46,14 @@ class TextSourceRange {
         return this.content;
     }
 
-    setEndOffset(length) {
-        const state = TextSourceRange.seekForward(this.range.startContainer, this.range.startOffset, length);
+    setEndOffset(length, fromEnd=false) {
+        const state = (
+            fromEnd ?
+            TextSourceRange.seekForward(this.range.endContainer, this.range.endOffset, length) :
+            TextSourceRange.seekForward(this.range.startContainer, this.range.startOffset, length)
+        );
         this.range.setEnd(state.node, state.offset);
-        this.content = state.content;
+        this.content = (fromEnd ? this.content + state.content : state.content);
         return length - state.remainder;
     }