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Fix offset handling of String#rindex with Regex #5594

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Merged
asterite merged 2 commits into from
Jan 23, 2018
Merged

Fix offset handling of String#rindex with Regex #5594

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2bf3339
Fix offset handling of String#rindex with Regex
straight-shoota Jan 16, 2018
3a9931d
Fix negative offset and remove substring
straight-shoota Jan 16, 2018
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15 changes: 13 additions & 2 deletions spec/std/string_spec.cr
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Original file line number Diff line number Diff line change
Expand Up @@ -707,24 +707,34 @@ describe "String" do

describe "rindex" do
describe "by char" do
it { "bbbb".rindex('b').should eq(3) }
it { "foobar".rindex('a').should eq(4) }
it { "foobar".rindex('g').should be_nil }
it { "日本語日本語".rindex('本').should eq(4) }
it { "あいう_えお".rindex('_').should eq(3) }

describe "with offset" do
it { "bbbb".rindex('b', 2).should eq(2) }
it { "abbbb".rindex('b', 0).should be_nil }
it { "abbbb".rindex('b', 1).should eq(1) }
it { "abbbb".rindex('a', 0).should eq(0) }
it { "faobar".rindex('a', 3).should eq(1) }
it { "faobarbaz".rindex('a', -3).should eq(4) }
it { "日本語日本語".rindex('本', 3).should eq(1) }
end
end

describe "by string" do
it { "bbbb".rindex("b").should eq(3) }
it { "foo baro baz".rindex("o b").should eq(7) }
it { "foo baro baz".rindex("fg").should be_nil }
it { "日本語日本語".rindex("日本").should eq(3) }

describe "with offset" do
it { "bbbb".rindex("b", 2).should eq(2) }
it { "abbbb".rindex("b", 0).should be_nil }
it { "abbbb".rindex("b", 1).should eq(1) }
it { "abbbb".rindex("a", 0).should eq(0) }
it { "foo baro baz".rindex("o b", 6).should eq(2) }
it { "foo".rindex("", 3).should eq(3) }
it { "foo".rindex("", 4).should eq(3) }
Expand All @@ -738,8 +748,9 @@ describe "String" do
it { "bbbb".rindex(/\d/).should be_nil }

describe "with offset" do
it { "bbbb".rindex(/b/, -3).should eq(2) }
it { "bbbb".rindex(/b/, -1235).should be_nil }
it { "bbbb".rindex(/b/, 2).should eq(2) }
it { "abbbb".rindex(/b/, 0).should be_nil }
it { "abbbb".rindex(/a/, 0).should eq(0) }
it { "日本語日本語".rindex(/日本/, 2).should eq(0) }
end
end
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5 changes: 2 additions & 3 deletions src/string.cr
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Expand Up @@ -2738,12 +2738,11 @@ class String
end

# ditto
def rindex(search : Regex, offset = 0)
offset += size if offset < 0

@RX14 RX14 Jan 16, 2018

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Why is this removed? You must support negative indexing from the end of the string.

@straight-shoota straight-shoota Jan 16, 2018

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The substring (self[0..offset]) handles negative indexes. There is no need to bother until we change that for a more performant implementation.

@RX14 RX14 Jan 16, 2018

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So why are the specs for negative indexes removed, and why do we have

return nil unless 0 <= offset <= size

which always returns nil for negative indexes?

@straight-shoota straight-shoota Jan 16, 2018

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Argh, true that won't work.

@straight-shoota straight-shoota Jan 16, 2018

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I think I'll just replace the implementation as suggested above. And add more specs...

def rindex(search : Regex, offset = size - 1)
return nil unless 0 <= offset <= size

match_result = nil
self[0, self.size - offset].scan(search) do |match_data|
self[0..offset].scan(search) do |match_data|
match_result = match_data
end

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