From f764b3aed25071a380ccce069eb9e3ee8d15bbfd Mon Sep 17 00:00:00 2001
From: Luis Lavena <luislavena@gmail.com>
Date: Sat, 30 Jan 2021 23:31:19 -0300
Subject: [PATCH] Fix incorrect lookup in non-root nodes

Given the following non-root tree:

  tree = Tree(Symbol).new
  tree.add "/prefix/", :prefix
  tree.add "/prefix/foo", :foo

Attempt to lookup for `/foo` was incorrectly identifying `:foo` entry as
the correct value.

This change ensures that child nodes of the current node are not scanned
if key and path being looked up do not match.

Fixes #27
---
 CHANGELOG.md            | 1 +
 spec/radix/tree_spec.cr | 9 +++++++++
 src/radix/tree.cr       | 8 ++++++++
 3 files changed, 18 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c5f44d2..6860007 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ so please check *Changed* and *Removed* notes before upgrading.
 
 ### Fixed
 - Correct lookup issue caused by partial shared key with glob [#23](https://github.com/luislavena/radix/issues/23)
+- Correct lookup caused by non-root key in suffix [#27](https://github.com/luislavena/radix/issues/27)
 
 ### Removed
 - Remove `Radix::Result#key` since exposes internal details about structure (breaking change)
diff --git a/spec/radix/tree_spec.cr b/spec/radix/tree_spec.cr
index f848f86..6191118 100644
--- a/spec/radix/tree_spec.cr
+++ b/spec/radix/tree_spec.cr
@@ -353,6 +353,15 @@ module Radix
           result.found?.should be_true
           result.payload.should eq(:tags)
         end
+
+        it "do not find when lookup for non-root key" do
+          tree = Tree(Symbol).new
+          tree.add "/prefix/", :prefix
+          tree.add "/prefix/foo", :foo
+
+          result = tree.find "/foo"
+          result.found?.should be_false
+        end
       end
 
       context "unicode nodes with shared parent" do
diff --git a/src/radix/tree.cr b/src/radix/tree.cr
index 3d930dd..9cd5194 100644
--- a/src/radix/tree.cr
+++ b/src/radix/tree.cr
@@ -299,6 +299,14 @@ module Radix
         end
       end
 
+      # determine if remaining part of key and path are still the same
+      if (key_reader.has_next? && path_reader.has_next?) &&
+         (key_reader.current_char != path_reader.current_char ||
+         key_reader.peek_next_char != path_reader.peek_next_char)
+        # path and key differ, skipping
+        return
+      end
+
       # still path to walk, check for possible trailing slash or children
       # nodes
       if path_reader.has_next?