d76213fb2d
The parser rejects an N-Quad with a comment, so we filter those out ahead of time. This simplifies the grammar and code generated by the parser.
76 lines
1.8 KiB
Go
76 lines
1.8 KiB
Go
// Copyright 2014 The Cayley Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package nquads
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import (
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"bufio"
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"bytes"
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"errors"
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"fmt"
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"io"
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"github.com/google/cayley/graph"
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)
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var (
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ErrAbsentSubject = errors.New("nqauds: absent subject")
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ErrAbsentPredicate = errors.New("nqauds: absent predicate")
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ErrAbsentObject = errors.New("nqauds: absent object")
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ErrUnterminated = errors.New("nqauds: unterminated quad")
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)
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// Parse returns a valid graph.Triple or a non-nil error.
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func Parse(str string) (*graph.Triple, error) {
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t, err := parse([]rune(str))
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return &t, err
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}
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type Decoder struct {
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r *bufio.Reader
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line []byte
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}
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func NewDecoder(r io.Reader) *Decoder {
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return &Decoder{r: bufio.NewReader(r)}
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}
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func (dec *Decoder) Unmarshal() (*graph.Triple, error) {
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dec.line = dec.line[:0]
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var line []byte
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for {
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for {
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l, pre, err := dec.r.ReadLine()
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if err != nil {
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return nil, err
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}
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dec.line = append(dec.line, l...)
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if !pre {
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break
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}
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}
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if line = bytes.TrimSpace(dec.line); len(line) != 0 && line[0] != '#' {
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break
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}
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dec.line = dec.line[:0]
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}
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triple, err := Parse(string(line))
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if err != nil {
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return nil, fmt.Errorf("failed to parse %q: %v", dec.line, err)
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}
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if triple == nil {
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return dec.Unmarshal()
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}
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return triple, nil
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}
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