From cef6827182d17f2a13649689403ce7a6fb8922a9 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Mon, 25 Aug 2014 09:31:27 -0700
Subject: [PATCH] Add find_for_range function for Nodes

---
 include/tree_sitter/runtime.h |  3 +-
 spec/runtime/node_spec.cc     | 55 +++++++++++++++++++++++++----------
 src/runtime/node.c            | 12 +++++---
 3 files changed, 49 insertions(+), 21 deletions(-)

diff --git a/include/tree_sitter/runtime.h b/include/tree_sitter/runtime.h
index fb2ee50c..6a3d5a36 100644
--- a/include/tree_sitter/runtime.h
+++ b/include/tree_sitter/runtime.h
@@ -29,7 +29,8 @@ size_t ts_node_size(const TSNode *);
 TSSymbol ts_node_sym(const TSNode *);
 TSNode *ts_node_child(TSNode *, size_t);
 size_t ts_node_child_count(const TSNode *);
-TSNode *ts_node_find_pos(TSNode *, size_t);
+TSNode *ts_node_find_for_pos(TSNode *, size_t);
+TSNode *ts_node_find_for_range(TSNode *, size_t, size_t);
 TSNode *ts_node_parent(TSNode *node);
 TSNode *ts_node_next_sibling(TSNode *node);
 TSNode *ts_node_prev_sibling(TSNode *node);
diff --git a/spec/runtime/node_spec.cc b/spec/runtime/node_spec.cc
index 2f816c30..24f389a6 100644
--- a/spec/runtime/node_spec.cc
+++ b/spec/runtime/node_spec.cc
@@ -92,26 +92,49 @@ describe("Node", []() {
     });
   });
 
-  describe("find_pos", [&]() {
-    it("can retrieve the leaf node at a given position", [&]() {
-      TSNode *number1 = ts_node_find_pos(root, 3);
-      TSNode *number2 = ts_node_find_pos(root, 7);
-
-      AssertThat(ts_node_name(number1), Equals("number"));
-      AssertThat(ts_node_size(number1), Equals<size_t>(2));
-
-      AssertThat(ts_node_name(number2), Equals("number"));
-      AssertThat(ts_node_size(number2), Equals<size_t>(1));
-
-      ts_node_release(number1);
-      ts_node_release(number2);
+  describe("find_for_range", [&]() {
+    describe("when there is a leaf node that spans the given range exactly", [&]() {
+      it("returns that leaf node", [&]() {
+        TSNode *number = ts_node_find_for_range(root, 10, 12);
+        AssertThat(ts_node_name(number), Equals("number"));
+        AssertThat(ts_node_size(number), Equals<size_t>(3));
+        AssertThat(ts_node_pos(number), Equals<size_t>(10));
+        ts_node_release(number);
+      });
     });
 
-    it("returns higher-level nodes when no leaf is at the given position", [&]() {
-      TSNode *node = ts_node_find_pos(root, 6);
+    describe("when there is a leaf node that extends beyond the given range", [&]() {
+      it("returns that leaf node", [&]() {
+        TSNode *number = ts_node_find_for_range(root, 10, 11);
+        AssertThat(ts_node_name(number), Equals("number"));
+        AssertThat(ts_node_size(number), Equals<size_t>(3));
+        AssertThat(ts_node_pos(number), Equals<size_t>(10));
+        ts_node_release(number);
 
+        number = ts_node_find_for_range(root, 11, 12);
+        AssertThat(ts_node_name(number), Equals("number"));
+        AssertThat(ts_node_size(number), Equals<size_t>(3));
+        AssertThat(ts_node_pos(number), Equals<size_t>(10));
+        ts_node_release(number);
+      });
+    });
+
+    describe("when there is no leaf node that spans the given range", [&]() {
+      it("returns the smallest node that does span the range", [&]() {
+        TSNode *node = ts_node_find_for_range(root, 6, 7);
+        AssertThat(ts_node_name(node), Equals("array"));
+        AssertThat(ts_node_pos(node), Equals<size_t>(2));
+        AssertThat(ts_node_size(node), Equals<size_t>(12));
+        ts_node_release(node);
+      });
+    });
+  });
+
+  describe("find_for_pos", [&]() {
+    it("finds the smallest node that spans the given position", [&]() {
+      TSNode *node = ts_node_find_for_pos(root, 6);
       AssertThat(ts_node_name(node), Equals("array"));
-
+      AssertThat(ts_node_pos(node), Equals<size_t>(2));
       ts_node_release(node);
     });
   });
diff --git a/src/runtime/node.c b/src/runtime/node.c
index ea67a032..b6b94117 100644
--- a/src/runtime/node.c
+++ b/src/runtime/node.c
@@ -77,19 +77,19 @@ TSNode *ts_node_child(TSNode *parent, size_t index) {
                       parent->names);
 }
 
-TSNode *ts_node_find_pos(TSNode *parent, size_t position) {
+TSNode *ts_node_find_for_range(TSNode *parent, size_t min, size_t max) {
   size_t child_count;
   TSChildWithPosition *children =
       ts_tree_visible_children(parent->content, &child_count);
   for (size_t i = 0; i < child_count; i++) {
     TSChildWithPosition child = children[i];
     size_t child_left = child.position + child.tree->offset;
-    if (child_left > position)
+    if (child_left > min)
       break;
-    if (child_left + child.tree->size > position) {
+    if (child_left + child.tree->size >= max) {
       TSNode *node =
           ts_node_make(child.tree, parent, i, child.position, parent->names);
-      TSNode *result = ts_node_find_pos(node, position);
+      TSNode *result = ts_node_find_for_range(node, min, max);
       ts_node_release(node);
       return result;
     }
@@ -98,3 +98,7 @@ TSNode *ts_node_find_pos(TSNode *parent, size_t position) {
   ts_node_retain(parent);
   return parent;
 }
+
+TSNode *ts_node_find_for_pos(TSNode *parent, size_t position) {
+  return ts_node_find_for_range(parent, position, position);
+}