lib/core/stream: LineIterator use CachedIterator
[nit.git] / lib / core / stream.nit
index 9b19dd3..b0486ef 100644 (file)
@@ -122,14 +122,81 @@ abstract class Reader
                for i in [0 .. max[ do
                        var b = raw_read_byte
                        if b < 0 then break
-                       buf[i] = b.to_b
+                       buf[i] = b
                        rd += 1
                end
                return rd
        end
 
        # Reads a character. Returns `null` on EOF or timeout
-       fun read_char: nullable Char is abstract
+       #
+       # Returns unicode replacement character '�' if an
+       # invalid byte sequence is read.
+       #
+       # `read_char` may block if:
+       #
+       # * No byte could be read from the current buffer
+       # * An incomplete char is partially read, and more bytes are
+       #   required for full decoding.
+       fun read_char: nullable Char do
+               if eof then return null
+               var cod = codec
+               var codet_sz = cod.codet_size
+               var lk = lookahead
+               var llen = lookahead_length
+               if llen < codet_sz then
+                       llen += raw_read_bytes(lk.fast_cstring(llen), codet_sz - llen)
+               end
+               if llen < codet_sz then
+                       lookahead_length = 0
+                       return 0xFFFD.code_point
+               end
+               var ret = cod.is_valid_char(lk, codet_sz)
+               var max_llen = cod.max_lookahead
+               while ret == 1 and llen < max_llen do
+                       var rd = raw_read_bytes(lk.fast_cstring(llen), codet_sz)
+                       if rd < codet_sz then
+                               llen -= codet_sz
+                               if llen > 0 then
+                                       lookahead.lshift(codet_sz, llen, codet_sz)
+                               end
+                               lookahead_length = llen.max(0)
+                               return 0xFFFD.code_point
+                       end
+                       llen += codet_sz
+                       ret = cod.is_valid_char(lk, llen)
+               end
+               if ret == 0 then
+                       var c = cod.decode_char(lk)
+                       var clen = c.u8char_len
+                       llen -= clen
+                       if llen > 0 then
+                               lookahead.lshift(clen, llen, clen)
+                       end
+                       lookahead_length = llen
+                       return c
+               end
+               if ret == 2 or ret == 1 then
+                       llen -= codet_sz
+                       if llen > 0 then
+                               lookahead.lshift(codet_sz, llen, codet_sz)
+                       end
+                       lookahead_length = llen
+                       return 0xFFFD.code_point
+               end
+               # Should not happen if the decoder works properly
+               var arr = new Array[Object]
+               arr.push "Decoder error: could not decode nor recover from byte sequence ["
+               for i in [0 .. llen[ do
+                       arr.push lk[i]
+                       arr.push ", "
+               end
+               arr.push "]"
+               var err = new IOError(arr.plain_to_s)
+               err.cause = last_error
+               last_error = err
+               return 0xFFFD.code_point
+       end
 
        # Reads a byte. Returns a negative value on error
        fun read_byte: Int do
@@ -148,13 +215,16 @@ abstract class Reader
 
        # Reads a String of at most `i` length
        fun read(i: Int): String do
+               assert i >= 0
                var cs = new CString(i)
                var rd = read_bytes_to_cstring(cs, i)
+               if rd < 0 then return ""
                return codec.decode_string(cs, rd)
        end
 
        # Reads up to `max` bytes from source
        fun read_bytes(max: Int): Bytes do
+               assert max >= 0
                var cs = new CString(max)
                var rd = read_bytes_to_cstring(cs, max)
                return new Bytes(cs, rd, max)
@@ -173,7 +243,7 @@ abstract class Reader
                else
                        lookahead_length = 0
                end
-               return rd + raw_read_bytes(bytes, max - rd)
+               return rd + raw_read_bytes(bytes.fast_cstring(rd), max - rd)
        end
 
        # Read a string until the end of the line.
@@ -345,7 +415,11 @@ abstract class Reader
 
        # Is there something to read.
        # This function returns 'false' if there is something to read.
-       fun eof: Bool is abstract
+       fun eof: Bool do
+               if lookahead_length > 0 then return false
+               lookahead_length = raw_read_bytes(lookahead, 1)
+               return lookahead_length <= 0
+       end
 
        # Read the next sequence of non whitespace characters.
        #
@@ -410,37 +484,18 @@ end
 # Iterator returned by `Reader::each_line`.
 # See the aforementioned method for details.
 class LineIterator
-       super Iterator[String]
+       super CachedIterator[String]
 
        # The original stream
        var stream: Reader
 
-       redef fun is_ok
+       redef fun next_item
        do
-               var res = not stream.eof
-               if not res and close_on_finish then stream.close
-               return res
-       end
-
-       redef fun item
-       do
-               var line = self.line
-               if line == null then
-                       line = stream.read_line
+               if stream.eof then
+                       if close_on_finish then stream.close
+                       return null
                end
-               self.line = line
-               return line
-       end
-
-       # The last line read (cache)
-       private var line: nullable String = null
-
-       redef fun next
-       do
-               # force the read
-               if line == null then item
-               # drop the line
-               line = null
+               return stream.read_line
        end
 
        # Close the stream when the stream is at the EOF.
@@ -467,17 +522,23 @@ end
 abstract class Writer
        super Stream
 
-       # Writes bytes from `s`
-       fun write_bytes(s: Bytes) is abstract
+       # Write bytes from `s`
+       fun write_bytes(s: Bytes) do write_bytes_from_cstring(s.items, s.length)
 
-       # write a string
+       # Write `len` bytes from `ns`
+       fun write_bytes_from_cstring(ns: CString, len: Int) is abstract
+
+       # Write a string
        fun write(s: Text) is abstract
 
        # Write a single byte
-       fun write_byte(value: Byte) is abstract
+       fun write_byte(value: Int) is abstract
 
-       # Writes a single char
-       fun write_char(c: Char) do write(c.to_s)
+       # Write a single char
+       fun write_char(c: Char) do
+               var ln = codec.add_char_to(c, write_buffer)
+               write_bytes_from_cstring(write_buffer, ln)
+       end
 
        # Can the stream be used to write
        fun is_writable: Bool is abstract
@@ -494,17 +555,32 @@ interface Writable
        # The specific logic it let to the concrete subclasses
        fun write_to(stream: Writer) is abstract
 
-       # Like `write_to` but return a new String (may be quite large)
+       # Like `write_to` but return a new String (may be quite large).
        #
-       # This funtionality is anectodical, since the point
-       # of streamable object to to be efficienlty written to a
-       # stream without having to allocate and concatenate strings
+       # This functionality is anecdotal, since the point
+       # of a streamable object is to be efficiently written to a
+       # stream without having to allocate and concatenate strings.
        fun write_to_string: String
        do
                var stream = new StringWriter
                write_to(stream)
                return stream.to_s
        end
+
+       # Like `write_to` but return a new Bytes (may be quite large)
+       #
+       # This functionality is anecdotal, since the point
+       # of a streamable object is to be efficiently written to a
+       # stream without having to allocate and concatenate buffers.
+       #
+       # Nevertheless, you might need this method if you want to know
+       # the byte size of a writable object.
+       fun write_to_bytes: Bytes
+       do
+               var stream = new BytesWriter
+               write_to(stream)
+               return stream.bytes
+       end
 end
 
 redef class Bytes
@@ -519,201 +595,6 @@ redef class Text
        redef fun write_to(stream) do stream.write(self)
 end
 
-# Input streams with a buffered input for efficiency purposes
-abstract class BufferedReader
-       super Reader
-       redef fun read_char
-       do
-               if last_error != null then return null
-               if eof then
-                       last_error = new IOError("Stream has reached eof")
-                       return null
-               end
-               # TODO: Fix when supporting UTF-8
-               var c = _buffer[_buffer_pos].to_i.code_point
-               _buffer_pos += 1
-               return c
-       end
-
-       redef fun read_byte
-       do
-               if last_error != null then return -1
-               if eof then
-                       last_error = new IOError("Stream has reached eof")
-                       return -1
-               end
-               var c = _buffer[_buffer_pos]
-               _buffer_pos += 1
-               return c.to_i
-       end
-
-       # Resets the internal buffer
-       fun buffer_reset do
-               _buffer_length = 0
-               _buffer_pos = 0
-       end
-
-       # Peeks up to `n` bytes in the buffer
-       #
-       # The operation does not consume the buffer
-       #
-       # ~~~nitish
-       # var x = new FileReader.open("File.txt")
-       # assert x.peek(5) == x.read(5)
-       # ~~~
-       fun peek(i: Int): Bytes do
-               if eof then return new Bytes.empty
-               var remsp = _buffer_length - _buffer_pos
-               if i <= remsp then
-                       var bf = new Bytes.with_capacity(i)
-                       bf.append_ns_from(_buffer, i, _buffer_pos)
-                       return bf
-               end
-               var bf = new Bytes.with_capacity(i)
-               bf.append_ns_from(_buffer, remsp, _buffer_pos)
-               _buffer_pos = _buffer_length
-               read_intern(i - bf.length, bf)
-               remsp = _buffer_length - _buffer_pos
-               var full_len = bf.length + remsp
-               if full_len > _buffer_capacity then
-                       var c = _buffer_capacity
-                       while c < full_len do c = c * 2 + 2
-                       _buffer_capacity = c
-               end
-               var nns = new CString(_buffer_capacity)
-               bf.items.copy_to(nns, bf.length, 0, 0)
-               _buffer.copy_to(nns, remsp, _buffer_pos, bf.length)
-               _buffer = nns
-               _buffer_pos = 0
-               _buffer_length = full_len
-               return bf
-       end
-
-       redef fun read_bytes_to_cstring(buf, i)
-       do
-               if last_error != null then return 0
-               var bbf = new Bytes(buf, 0, i)
-               return read_intern(i, bbf)
-       end
-
-       # Fills `buf` with at most `i` bytes read from `self`
-       private fun read_intern(i: Int, buf: Bytes): Int do
-               if eof then return 0
-               var p = _buffer_pos
-               var bufsp = _buffer_length - p
-               if bufsp >= i then
-                       _buffer_pos += i
-                       buf.append_ns_from(_buffer, i, p)
-                       return i
-               end
-               _buffer_pos = _buffer_length
-               var readln = _buffer_length - p
-               buf.append_ns_from(_buffer, readln, p)
-               var rd = read_intern(i - readln, buf)
-               return rd + readln
-       end
-
-       redef fun read_all_bytes
-       do
-               if last_error != null then return new Bytes.empty
-               var s = new Bytes.with_capacity(10)
-               var b = _buffer
-               while not eof do
-                       var j = _buffer_pos
-                       var k = _buffer_length
-                       var rd_sz = k - j
-                       s.append_ns_from(b, rd_sz, j)
-                       _buffer_pos = k
-                       fill_buffer
-               end
-               return s
-       end
-
-       redef fun append_line_to(s)
-       do
-               var lb = new Bytes.with_capacity(10)
-               loop
-                       # First phase: look for a '\n'
-                       var i = _buffer_pos
-                       while i < _buffer_length and _buffer[i] != 0xAu8 do
-                               i += 1
-                       end
-
-                       var eol
-                       if i < _buffer_length then
-                               assert _buffer[i] == 0xAu8
-                               i += 1
-                               eol = true
-                       else
-                               eol = false
-                       end
-
-                       # if there is something to append
-                       if i > _buffer_pos then
-                               # Copy from the buffer to the string
-                               var j = _buffer_pos
-                               while j < i do
-                                       lb.add(_buffer[j])
-                                       j += 1
-                               end
-                               _buffer_pos = i
-                       else
-                               assert end_reached
-                               s.append lb.to_s
-                               return
-                       end
-
-                       if eol then
-                               # so \n is found
-                               s.append lb.to_s
-                               return
-                       else
-                               # so \n is not found
-                               if end_reached then
-                                       s.append lb.to_s
-                                       return
-                               end
-                               fill_buffer
-                       end
-               end
-       end
-
-       redef fun eof
-       do
-               if _buffer_pos < _buffer_length then return false
-               if end_reached then return true
-               fill_buffer
-               return _buffer_pos >= _buffer_length and end_reached
-       end
-
-       # The buffer
-       private var buffer: CString = new CString(0)
-
-       # The current position in the buffer
-       private var buffer_pos = 0
-
-       # Length of the current buffer (i.e. nuber of bytes in the buffer)
-       private var buffer_length = 0
-
-       # Capacity of the buffer
-       private var buffer_capacity = 0
-
-       # Fill the buffer
-       protected fun fill_buffer is abstract
-
-       # Has the last fill_buffer reached the end
-       protected fun end_reached: Bool is abstract
-
-       # Allocate a `_buffer` for a given `capacity`.
-       protected fun prepare_buffer(capacity: Int)
-       do
-               _buffer = new CString(capacity)
-               _buffer_pos = 0 # need to read
-               _buffer_length = 0
-               _buffer_capacity = capacity
-       end
-end
-
 # A `Stream` that can be written to and read from
 abstract class Duplex
        super Reader
@@ -727,7 +608,7 @@ end
 #
 # writer.write "Strings "
 # writer.write_char '&'
-# writer.write_byte 0x20u8
+# writer.write_byte 0x20
 # writer.write_bytes "bytes".to_bytes
 #
 # assert writer.to_s == "\\x53\\x74\\x72\\x69\\x6E\\x67\\x73\\x20\\x26\\x20\\x62\\x79\\x74\\x65\\x73"
@@ -741,12 +622,12 @@ end
 # writer = new BytesWriter
 #
 # # Write just the character first half
-# writer.write_byte 0xC2u8
+# writer.write_byte 0xC2
 # assert writer.to_s == "\\xC2"
 # assert writer.bytes.to_s == "�"
 #
 # # Complete the character
-# writer.write_byte 0xA2u8
+# writer.write_byte 0xA2
 # assert writer.to_s == "\\xC2\\xA2"
 # assert writer.bytes.to_s == "¢"
 # ~~~
@@ -776,10 +657,9 @@ class BytesWriter
                bytes.add value
        end
 
-       redef fun write_bytes(b)
-       do
+       redef fun write_bytes_from_cstring(ns, len) do
                if closed then return
-               bytes.append b
+               bytes.append_ns(ns, len)
        end
 
        # Is the stream closed?
@@ -799,7 +679,7 @@ end
 #
 # writer.write "Strings "
 # writer.write_char '&'
-# writer.write_byte 0x20u8
+# writer.write_byte 0x20
 # writer.write_bytes "bytes".to_bytes
 #
 # assert writer.to_s == "Strings & bytes"
@@ -829,17 +709,7 @@ class BytesReader
        # The current position in `bytes`
        private var cursor = 0
 
-       redef fun read_char
-       do
-               if cursor >= bytes.length then return null
-
-               var len = bytes.items.length_of_char_at(cursor)
-               var char = bytes.items.char_at(cursor)
-               cursor += len
-               return char
-       end
-
-       redef fun read_byte
+       redef fun raw_read_byte
        do
                if cursor >= bytes.length then return -1