Add IO::Stapled (#6017)

* Add IO::Stapled * fixup! Add IO::Stapled * fixup! Add IO::Stapled
crystal-lang · Apr 29, 2018 · 981c343 · 981c343
1 parent db0dc67
commit 981c343
Show file tree

Hide file tree

Showing 2 changed files with 234 additions and 0 deletions.
diff --git a/spec/std/io/stapled_spec.cr b/spec/std/io/stapled_spec.cr
@@ -0,0 +1,112 @@
+require "spec"
+
+describe IO::Stapled do
+  it "combines two IOs" do
+    writer = IO::Memory.new
+    io = IO::Stapled.new IO::Memory.new("paul"), writer
+    io.gets.should eq "paul"
+    io << "peter"
+    writer.to_s.should eq "peter"
+  end
+
+  it "loops back" do
+    io = IO::Stapled.new(*IO.pipe)
+    io.puts "linus"
+    io.gets.should eq "linus"
+  end
+
+  describe "#close" do
+    it "does not close underlying IOs" do
+      reader, writer = IO::Memory.new, IO::Memory.new
+      io = IO::Stapled.new reader, writer
+      io.sync_close?.should be_false
+      io.close
+      io.closed?.should be_true
+      reader.closed?.should be_false
+      writer.closed?.should be_false
+    end
+
+    it "closes underlying IOs when sync_close is true" do
+      reader, writer = IO::Memory.new, IO::Memory.new
+      io = IO::Stapled.new reader, writer, sync_close: true
+      io.sync_close?.should be_true
+      io.close
+      io.closed?.should be_true
+      reader.closed?.should be_true
+      writer.closed?.should be_true
+    end
+
+    it "stops access to underlying IOs" do
+      reader, writer = IO::Memory.new("cle"), IO::Memory.new
+      io = IO::Stapled.new reader, writer
+      io.close
+      io.closed?.should be_true
+      reader.closed?.should be_false
+      writer.closed?.should be_false
+
+      expect_raises(IO::Error, "Closed stream") do
+        io.gets
+      end
+      expect_raises(IO::Error, "Closed stream") do
+        io.peek
+      end
+      expect_raises(IO::Error, "Closed stream") do
+        io << "closed"
+      end
+    end
+  end
+
+  it "#sync_close?" do
+    reader, writer = IO::Memory.new, IO::Memory.new
+    io = IO::Stapled.new reader, writer
+    io.sync_close = false
+    io.sync_close?.should be_false
+    io.sync_close = true
+    io.sync_close?.should be_true
+    io.close
+    reader.closed?.should be_true
+    writer.closed?.should be_true
+  end
+
+  it "#peek delegates to reader" do
+    reader = IO::Memory.new "cletus"
+    io = IO::Stapled.new reader, IO::Memory.new
+    io.peek.should eq "cletus".to_slice
+    io.gets
+    io.peek.should eq Bytes.empty
+  end
+
+  describe ".pipe" do
+    it "creates a bidirectional pipe" do
+      a, b = IO::Stapled.pipe
+      begin
+        a.sync_close?.should be_true
+        b.sync_close?.should be_true
+        a.puts "john"
+        b.gets.should eq "john"
+        b.puts "paul"
+        a.gets.should eq "paul"
+      ensure
+        a.close
+        b.close
+      end
+    end
+
+    it "with block creates a bidirectional pipe" do
+      ext_a, ext_b = nil, nil
+      IO::Stapled.pipe do |a, b|
+        ext_a, ext_b = a, b
+        a.sync_close?.should be_true
+        b.sync_close?.should be_true
+        a.puts "john"
+        b.gets.should eq "john"
+        b.puts "paul"
+        a.gets.should eq "paul"
+        a.sync_close = false
+        b.sync_close = false
+      end
+      ext_a.not_nil!.closed?.should be_true
+      ext_b.not_nil!.closed?.should be_true
+    end
+  end
+end
diff --git a/src/io/stapled.cr b/src/io/stapled.cr
@@ -0,0 +1,122 @@
+# This class staples together two unidirectional `IO`s to form a single,
+# bidirectional `IO`.
+#
+# Example (loopback):
+# ```
+# io = IO::Stapled.new(*IO.pipe)
+# io.puts "linus"
+# io.gets # => "linus"
+# ```
+#
+# Most methods simply delegate to the underlying `IO`s.
+class IO::Stapled < IO
+  # If `#sync_close?` is `true`, closing this `IO` will close the underlying `IO`s.
+  property? sync_close : Bool
+
+  # Returns `true` if this `IO` is closed.
+  #
+  # Underlying ÌO`s might have a different status.
+  getter? closed : Bool = false
+
+  # Creates a new `IO::Stapled` which reads from *reader*  and writes to *writer*-
+  def initialize(@reader : IO, @writer : IO, @sync_close : Bool = false)
+  end
+
+  # Reads a single byte from `reader`.
+  def read_byte : UInt8?
+    check_open
+
+    @reader.read_byte
+  end
+
+  # Reads a slice from `reader`.
+  def read(slice : Bytes)
+    check_open
+
+    @reader.read(slice)
+  end
+
+  # Gets a string from `reader`.
+  def gets(delimiter : Char, limit : Int, chomp = false) : String?
+    check_open
+
+    @reader.gets(delimiter, limit, chomp)
+  end
+
+  # Peeks into *reader*.
+  def peek : Bytes?
+    check_open
+
+    @reader.peek
+  end
+
+  # Skips `reader`.
+  def skip(bytes_count : Int) : Nil
+    check_open
+
+    @reader.skip(bytes_count)
+  end
+
+  # Writes a byte to `writer`.
+  def write_byte(byte : UInt8) : Nil
+    check_open
+
+    @writer.write_byte(byte)
+  end
+
+  # Writes a slice to `writer`.
+  def write(slice : Bytes) : Nil
+    check_open
+
+    @writer.write(slice)
+  end
+
+  # `Flushes `writer`.
+  def flush : self
+    check_open
+
+    @writer.flush
+
+    self
+  end
+
+  # Closes this ÌO`.
+  #
+  # If `sync_close?` is `true`it will also close the underlying ÌO`s.
+  def close : Nil
+    return if @closed
+    @closed = true
+
+    if @sync_close
+      @reader.close
+      @writer.close
+    end
+  end
+
+  # Creates a pair of bidirectional pipe endpoints connected with each other
+  # and passes them to the given block.
+  #
+  # Both endpoints and the underlying ÌO`s are closed after the block
+  # (even if `sync_close?` is `false`).
+  def self.pipe(read_blocking : Bool = false, write_blocking : Bool = false)
+    IO.pipe(read_blocking, write_blocking) do |a_read, a_write|
+      IO.pipe(read_blocking, write_blocking) do |b_read, b_write|
+        a, b = new(a_read, b_write, true), new(b_read, a_write, true)
+        begin
+          yield a, b
+        ensure
+          a.close
+          b.close
+        end
+      end
+    end
+  end
+
+  # Creates a pair of bidirectional pipe endpoints connected with each other
+  # and returns them in a `Tuple`.
+  def self.pipe(read_blocking : Bool = false, write_blocking : Bool = false) : {self, self}
+    a_read, a_write = IO.pipe(read_blocking, write_blocking)
+    b_read, b_write = IO.pipe(read_blocking, write_blocking)
+    return new(a_read, b_write, true), new(b_read, a_write, true)
+  end
+end