Add String#bytesplice with tests.

CHANGELOG.md

@@ -14,6 +14,7 @@ Compatibility:
 * Add support for array pattern matching. This is opt-in via `--pattern-matching` since pattern matching is not fully supported yet. (#2683, @razetime).
 * Fix `Array#[]` with `ArithmeticSequence` argument when step is negative (@itarato).
 * Fix `Range#size` and return `nil` for beginningless Range when end isn't Numeric (@rwstauner).
+* Add `String#bytesplice` (@itarato).
 
 Performance:
 

spec/ruby/core/string/bytesplice_spec.rb

@@ -0,0 +1,130 @@
+# -*- encoding: utf-8 -*-
+require_relative '../../spec_helper'
+
+describe "String#bytesplice" do
+  ruby_version_is "3.2" do
+    it "raises IndexError when index is less than -size" do
+      -> { "hello".bytesplice(-6, 0, "xxx") }.should raise_error(IndexError, "index -6 out of string")
+    end
+
+    it "raises IndexError when index is greater or equal to size" do
+      -> { "hello".bytesplice(6, 0, "xxx") }.should raise_error(IndexError, "index 6 out of string")
+    end
+
+    it "replaces with integer indices" do
+      "hello".bytesplice(-5, 0, "xxx").should == "xxxhello"
+      "hello".bytesplice(0, 0, "xxx").should == "xxxhello"
+      "hello".bytesplice(0, 1, "xxx").should == "xxxello"
+      "hello".bytesplice(0, 5, "xxx").should == "xxx"
+      "hello".bytesplice(0, 6, "xxx").should == "xxx"
+    end
+
+    it "raises RangeError when range left boundary is less than -size" do
+      -> { "hello".bytesplice(-6...-6, "xxx") }.should raise_error(RangeError, "-6...-6 out of range")
+    end
+
+    it "replaces with ranges" do
+      "hello".bytesplice(-5...-5, "xxx").should == "xxxhello"
+      "hello".bytesplice(0...0, "xxx").should == "xxxhello"
+      "hello".bytesplice(0..0, "xxx").should == "xxxello"
+      "hello".bytesplice(0...1, "xxx").should == "xxxello"
+      "hello".bytesplice(0..1, "xxx").should == "xxxllo"
+      "hello".bytesplice(0..-1, "xxx").should == "xxx"
+      "hello".bytesplice(0...5, "xxx").should == "xxx"
+      "hello".bytesplice(0...6, "xxx").should == "xxx"
+    end
+
+    it "raises TypeError when integer index is provided without length argument" do
+      -> { "hello".bytesplice(0, "xxx") }.should raise_error(TypeError, "wrong argument type Integer (expected Range)")
+    end
+
+    it "replaces on an empty string" do
+      "".bytesplice(0, 0, "").should == ""
+      "".bytesplice(0, 0, "xxx").should == "xxx"
+    end
+
+    it "mutates self" do
+      s = "hello"
+      s.bytesplice(2, 1, "xxx").should == "hexxxlo"
+      s.should == "hexxxlo"
+    end
+
+    it "raises when string is frozen" do
+      s = "hello".freeze
+      -> { s.bytesplice(2, 1, "xxx") }.should raise_error(FrozenError, "can't modify frozen String: \"hello\"")
+    end
+  end
+end
+
+describe "String#bytesplice with multibyte characters" do
+  ruby_version_is "3.2" do
+    it "raises IndexError when index is out of byte size boundary" do
+      -> { "こんにちは".bytesplice(-16, 0, "xxx") }.should raise_error(IndexError, "index -16 out of string")
+    end
+
+    it "raises IndexError when index is not on a codepoint boundary" do
+      -> { "こんにちは".bytesplice(1, 0, "xxx") }.should raise_error(IndexError, "offset 1 does not land on character boundary")
+    end
+
+    it "raises IndexError when length is not matching the codepoint boundary" do
+      -> { "こんにちは".bytesplice(0, 1, "xxx") }.should raise_error(IndexError, "offset 1 does not land on character boundary")
+      -> { "こんにちは".bytesplice(0, 2, "xxx") }.should raise_error(IndexError, "offset 2 does not land on character boundary")
+    end
+
+    it "replaces with integer indices" do
+      "こんにちは".bytesplice(-15, 0, "xxx").should == "xxxこんにちは"
+      "こんにちは".bytesplice(0, 0, "xxx").should == "xxxこんにちは"
+      "こんにちは".bytesplice(0, 3, "xxx").should == "xxxんにちは"
+      "こんにちは".bytesplice(3, 3, "はは").should == "こははにちは"
+      "こんにちは".bytesplice(15, 0, "xxx").should == "こんにちはxxx"
+    end
+
+    it "replaces with range" do
+      "こんにちは".bytesplice(-15...-16, "xxx").should == "xxxこんにちは"
+      "こんにちは".bytesplice(0...0, "xxx").should == "xxxこんにちは"
+      "こんにちは".bytesplice(0..2, "xxx").should == "xxxんにちは"
+      "こんにちは".bytesplice(0...3, "xxx").should == "xxxんにちは"
+      "こんにちは".bytesplice(0..5, "xxx").should == "xxxにちは"
+      "こんにちは".bytesplice(0..-1, "xxx").should == "xxx"
+      "こんにちは".bytesplice(0...15, "xxx").should == "xxx"
+      "こんにちは".bytesplice(0...18, "xxx").should == "xxx"
+    end
+
+    it "treats negative length for range as 0" do
+      "こんにちは".bytesplice(0...-100, "xxx").should == "xxxこんにちは"
+      "こんにちは".bytesplice(3...-100, "xxx").should == "こxxxんにちは"
+      "こんにちは".bytesplice(-15...-100, "xxx").should == "xxxこんにちは"
+    end
+
+    it "raises when ranges not match codepoint boundaries" do
+      -> { "こんにちは".bytesplice(0..0, "x") }.should raise_error(IndexError, "offset 1 does not land on character boundary")
+      -> { "こんにちは".bytesplice(0..1, "x") }.should raise_error(IndexError, "offset 2 does not land on character boundary")
+      # Begin is incorrect
+      -> { "こんにちは".bytesplice(-4..-1, "x") }.should raise_error(IndexError, "offset 11 does not land on character boundary")
+      -> { "こんにちは".bytesplice(-5..-1, "x") }.should raise_error(IndexError, "offset 10 does not land on character boundary")
+      # End is incorrect
+      -> { "こんにちは".bytesplice(-3..-2, "x") }.should raise_error(IndexError, "offset 14 does not land on character boundary")
+      -> { "こんにちは".bytesplice(-3..-3, "x") }.should raise_error(IndexError, "offset 13 does not land on character boundary")
+    end
+
+    it "deals with a different encoded argument" do
+      s = "こんにちは"
+      s.encoding.should == Encoding::UTF_8
+      sub = "xxxxxx"
+      sub.force_encoding(Encoding::US_ASCII)
+
+      result = s.bytesplice(0, 3, sub)
+      result.should == "xxxxxxんにちは"
+      result.encoding.should == Encoding::UTF_8
+
+      s = "xxxxxx"
+      s.force_encoding(Encoding::US_ASCII)
+      sub = "こんにちは"
+      sub.encoding.should == Encoding::UTF_8
+
+      result = s.bytesplice(0, 3, sub)
+      result.should == "こんにちはxxx"
+      result.encoding.should == Encoding::UTF_8
+    end
+  end
+end

spec/truffle/methods/String.txt

@@ -15,6 +15,7 @@ b
 bytes
 bytesize
 byteslice
+bytesplice
 capitalize
 capitalize!
 casecmp

src/main/ruby/truffleruby/core/string.rb

@@ -70,6 +70,54 @@ def byteslice(index_or_range, length = undefined)
     byteslice index, length
   end
 
+  def bytesplice(*args)
+    is_range = Primitive.is_a?(args[0], Range)
+
+    if args.size == 3
+      start = Primitive.rb_to_int(args[0])
+      start += bytesize if start < 0
+
+      len = Primitive.rb_to_int(args[1])
+      str = StringValue(args[2])
+    elsif args.size == 2
+      unless is_range
+        raise(TypeError, "wrong argument type #{Primitive.class(args[0])} (expected Range)")
+      end
+
+      start, len = Primitive.range_normalized_start_length(args[0], bytesize)
+      len = 0 if len < 0
+      str = StringValue(args[1])
+    else
+      raise(ArgumentError, "wrong number of arguments (given #{args.size}, expected 2..3)")
+    end
+
+    if len < 0
+      raise(IndexError, "negative length #{len}")
+    end
+
+    if bytesize < start || start < 0
+      if is_range
+        raise(RangeError, "#{args[0]} out of range")
+      else
+        raise(IndexError, "index #{args[0]} out of string")
+      end
+    end
+
+    len = bytesize - start if len > bytesize - start
+    finish = start + len
+
+    unless Truffle::StringOperations.on_codepoint_boundary?(self, start)
+      raise(IndexError, "offset #{start} does not land on character boundary")
+    end
+    unless Truffle::StringOperations.on_codepoint_boundary?(self, finish)
+      raise(IndexError, "offset #{finish} does not land on character boundary")
+    end
+
+    Primitive.check_mutable_string(self)
+    enc = Primitive.encoding_ensure_compatible_str(self, str)
+    Primitive.string_splice(self, str, start, len, enc)
+  end
+
   def self.try_convert(obj)
     Truffle::Type.try_convert obj, String, :to_str
   end

src/main/ruby/truffleruby/core/truffle/polyglot_methods.rb

@@ -80,6 +80,10 @@ def byteslice(...)
       to_s.byteslice(...)
     end
 
+    def bytesplice(...)
+      to_s.bytesplice(...)
+    end
+
     def capitalize(...)
       to_s.capitalize(...)
     end

src/main/ruby/truffleruby/core/truffle/string_operations.rb

@@ -411,5 +411,18 @@ def self.assign_regexp(string, index, count, replacement)
 
       Primitive.string_splice(string, replacement, bi, bs, enc)
     end
+
+    def self.on_codepoint_boundary?(string, byte_pos)
+      char_pos = Primitive.byte_index_to_character_index(string, byte_pos)
+      adjusted_byte_pos = if char_pos >= string.size
+                            # Handle index overflow cases.
+                            # @see com.oracle.truffle.api.strings.ByteIndexToCodePointIndexNode#execute for details.
+                            string.bytesize
+                          else
+                            Primitive.character_index_to_byte_index(string, char_pos)
+                          end
+
+      byte_pos == adjusted_byte_pos
+    end
   end
 end