Indexable: fixed a few issues

crystal-lang · Aug 4, 2016 · 4db88ed · 4db88ed
1 parent f104e7a
commit 4db88ed
Showing 2 changed files with 39 additions and 0 deletions.
diff --git a/spec/std/indexable_spec.cr b/spec/std/indexable_spec.cr
@@ -0,0 +1,37 @@
+require "spec"
+
+class SafeIndexable
+  include Indexable(Int32)
+
+  getter size
+
+  def initialize(@size : Int32)
+  end
+
+  def unsafe_at(i)
+    raise IndexError.new unless 0 <= i < size
+    i
+  end
+end
+
+describe Indexable do
+  it "does index with big negative offset" do
+    indexable = SafeIndexable.new(3)
+    indexable.index(0, -100).should be_nil
+  end
+
+  it "does index with big offset" do
+    indexable = SafeIndexable.new(3)
+    indexable.index(0, 100).should be_nil
+  end
+
+  it "does rindex with big negative offset" do
+    indexable = SafeIndexable.new(3)
+    indexable.rindex(0, -100).should be_nil
+  end
+
+  it "does rindex with big offset" do
+    indexable = SafeIndexable.new(3)
+    indexable.rindex(0, 100).should be_nil
+  end
+end
diff --git a/src/indexable.cr b/src/indexable.cr
@@ -290,6 +290,7 @@ module Indexable(T)
   # ```
   def index(offset : Int = 0)
     offset += size if offset < 0
+    return nil if offset < 0
 
     offset.upto(size - 1) do |i|
       if yield unsafe_at(i)
@@ -369,6 +370,7 @@ module Indexable(T)
   # ```
   def rindex(offset = size - 1)
     offset += size if offset < 0
+    return nil if offset >= size
 
     offset.downto(0) do |i|
       if yield unsafe_at(i)