Create quads hierarchy

* Move nquads into quad.
* Create cquads simplified parser in quad.
* Move Triple (renamed Quad) to quad.

Also made sure mongo actually implements BulkLoader.

quad/cquads/cquads.go

@@ -0,0 +1,141 @@
+// Copyright 2014 The Cayley Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package cquads implements parsing N-Quads like line-based syntax
+// for RDF datasets.
+//
+// N-Quad parsing is performed as based on a simplified grammar derived from
+// the N-Quads grammar defined by http://www.w3.org/TR/n-quads/.
+//
+// For a complete definition of the grammar, see cquads.rl.
+package cquads
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"strconv"
+
+	"github.com/google/cayley/quad"
+)
+
+// Parse returns a valid quad.Quad or a non-nil error. Parse does
+// handle comments except where the comment placement does not prevent
+// a complete valid quad.Quad from being defined.
+func Parse(str string) (*quad.Quad, error) {
+	q, err := parse([]rune(str))
+	return &q, err
+}
+
+// Decoder implements simplified N-Quad document parsing.
+type Decoder struct {
+	r    *bufio.Reader
+	line []byte
+}
+
+// NewDecoder returns an N-Quad decoder that takes its input from the
+// provided io.Reader.
+func NewDecoder(r io.Reader) *Decoder {
+	return &Decoder{r: bufio.NewReader(r)}
+}
+
+// Unmarshal returns the next valid N-Quad as a quad.Quad, or an error.
+func (dec *Decoder) Unmarshal() (*quad.Quad, error) {
+	dec.line = dec.line[:0]
+	var line []byte
+	for {
+		for {
+			l, pre, err := dec.r.ReadLine()
+			if err != nil {
+				return nil, err
+			}
+			dec.line = append(dec.line, l...)
+			if !pre {
+				break
+			}
+		}
+		if line = bytes.TrimSpace(dec.line); len(line) != 0 && line[0] != '#' {
+			break
+		}
+		dec.line = dec.line[:0]
+	}
+	triple, err := Parse(string(line))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse %q: %v", dec.line, err)
+	}
+	if triple == nil {
+		return dec.Unmarshal()
+	}
+	return triple, nil
+}
+
+func unEscape(r []rune, isQuoted, isEscaped bool) string {
+	if isQuoted {
+		r = r[1 : len(r)-1]
+	}
+	if !isEscaped {
+		return string(r)
+	}
+
+	buf := bytes.NewBuffer(make([]byte, 0, len(r)))
+
+	for i := 0; i < len(r); {
+		switch r[i] {
+		case '\\':
+			i++
+			var c byte
+			switch r[i] {
+			case 't':
+				c = '\t'
+			case 'b':
+				c = '\b'
+			case 'n':
+				c = '\n'
+			case 'r':
+				c = '\r'
+			case 'f':
+				c = '\f'
+			case '"':
+				c = '"'
+			case '\'':
+				c = '\''
+			case '\\':
+				c = '\\'
+			case 'u':
+				rc, err := strconv.ParseInt(string(r[i+1:i+5]), 16, 32)
+				if err != nil {
+					panic(fmt.Errorf("internal parser error: %v", err))
+				}
+				buf.WriteRune(rune(rc))
+				i += 5
+				continue
+			case 'U':
+				rc, err := strconv.ParseInt(string(r[i+1:i+9]), 16, 32)
+				if err != nil {
+					panic(fmt.Errorf("internal parser error: %v", err))
+				}
+				buf.WriteRune(rune(rc))
+				i += 9
+				continue
+			}
+			buf.WriteByte(c)
+		default:
+			buf.WriteRune(r[i])
+		}
+		i++
+	}
+
+	return buf.String()
+}