split the project from the main cayley repository

Signed-off-by: Denys Smirnov <denis.smirnov.91@gmail.com>

Author: dennwc

.gitignore

@@ -0,0 +1,7 @@
+*.swp
+main
+*.test
+*.peg.go
+.DS_Store
+
+vendor/

.travis.yml

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+language: go
+
+go:
+  - "1.12.x"
+  - "1.13.x"
+  - tip
+
+matrix:
+  allow_failures:
+    - go: tip
+
+install:
+  - GO111MODULE=on go mod download
+
+cache:
+  directories:
+    - $GOPATH/pkg/mod
+
+script:
+  - GO111MODULE=on go test -v ./...

CODEOWNERS

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+*   @dennwc

LICENSE

@@ -0,0 +1,175 @@
+
+                                 Apache License
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+                        http://www.apache.org/licenses/
+
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+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
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+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
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+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
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+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
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+      other commercial damages or losses), even if such Contributor
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+   9. Accepting Warranty or Additional Liability. While redistributing
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+      on Your own behalf and on Your sole responsibility, not on behalf
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+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.

README.md

@@ -0,0 +1,22 @@
+# Quad formats for Go
+
+[![Build Status](https://travis-ci.com/cayleygraph/quad.svg?branch=master)](https://travis-ci.com/cayleygraph/quad)
+
+This library provides encoding and decoding support for NQuad/NTriple-compatible formats.
+
+## Supported formats
+
+ID  | Name | Read | Write | Ext
+--- | ---- | ---- | ----- | ---
+`nquads` | NQuads | + | + | `.nq`, `.nt`
+`jsonld` | JSON-LD | + | + | `.jsonld`
+`graphviz` | DOT/Graphviz | - | + | `.gv`, `.dot`
+`gml` | GML | - | + | `.gml`
+`graphml` | GraphML | - | + | `.graphml`
+`pquads` | ProtoQuads | + | + | `.pq`
+`json` | JSON | + | + | `.json`
+`json-stream` | JSON Stream | + | + | -
+
+## Community
+
+* Slack: [cayleygraph.slack.com](https://cayleygraph.slack.com) -- Invite [here](https://cayley-slackin.herokuapp.com/)

dot/dot.go

@@ -0,0 +1,94 @@
+// Package dot provides an encoder for DOT format (graphviz).
+package dot
+
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/cayleygraph/quad"
+)
+
+func init() {
+	quad.RegisterFormat(quad.Format{
+		Name:   "graphviz",
+		Ext:    []string{".gv", ".dot"},
+		Writer: func(w io.Writer) quad.WriteCloser { return NewWriter(w) },
+	})
+}
+
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{w: w}
+}
+
+type Writer struct {
+	w       io.Writer
+	written bool
+	err     error
+}
+
+var escaper = strings.NewReplacer(
+	`\`, `\\`,
+	`"`, `\"`,
+)
+
+func escape(s string) string {
+	return `"` + escaper.Replace(s) + `"`
+}
+
+func (w *Writer) writeString(s string) {
+	if w.err != nil {
+		return
+	}
+	_, w.err = w.w.Write([]byte(s))
+}
+
+func (w *Writer) WriteQuad(q quad.Quad) error {
+	if w.err != nil {
+		return w.err
+	}
+	if !w.written {
+		if _, err := w.w.Write([]byte(header)); err != nil {
+			return err
+		}
+		w.written = true
+	}
+	// TODO: use label
+	w.writeString("\t")
+	w.writeString(escape(q.Subject.String()))
+	w.writeString(" -> ")
+	w.writeString(escape(q.Object.String()))
+	w.writeString(" [ label = ")
+	w.writeString(escape(q.Predicate.String()))
+	w.writeString(" ];\n")
+	return w.err
+}
+
+func (w *Writer) WriteQuads(buf []quad.Quad) (int, error) {
+	for i, q := range buf {
+		if err := w.WriteQuad(q); err != nil {
+			return i, err
+		}
+	}
+	return len(buf), nil
+}
+
+func (w *Writer) Close() error {
+	if w.err != nil {
+		return w.err
+	}
+	if !w.written {
+		if _, w.err = w.w.Write([]byte(header)); w.err != nil {
+			return w.err
+		}
+	}
+	if _, w.err = w.w.Write([]byte(footer)); w.err != nil {
+		return w.err
+	}
+	w.err = fmt.Errorf("closed")
+	return nil
+}
+
+const header = `digraph cayley_graph {
+`
+const footer = "}\n"

dot/dot_test.go

@@ -0,0 +1,71 @@
+package dot_test
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/cayleygraph/quad"
+	"github.com/cayleygraph/quad/dot"
+)
+
+var testData = []struct {
+	quads []quad.Quad
+	data  string
+}{
+	{
+		[]quad.Quad{
+			{
+				Subject:   quad.BNode("subject1"),
+				Predicate: quad.IRI("/film/performance/character"),
+				Object:    quad.String("Tomas de Torquemada"),
+				Label:     nil,
+			},
+			{
+				Subject:   quad.BNode("subject1"),
+				Predicate: quad.IRI("http://an.example/predicate1"),
+				Object:    quad.String("object1"),
+				Label:     nil,
+			},
+			{
+				Subject:   quad.IRI("http://example.org/bob#me"),
+				Predicate: quad.IRI("http://schema.org/birthDate"),
+				Object: quad.TypedString{
+					Value: "1990-07-04",
+					Type:  "http://www.w3.org/2001/XMLSchema#date",
+				},
+				Label: nil,
+			},
+			{
+				Subject:   quad.BNode("subject1"),
+				Predicate: quad.IRI("text"),
+				Object:    quad.String(`some "text"`),
+				Label:     nil,
+			},
+		},
+		`digraph cayley_graph {
+	"_:subject1" -> "\"Tomas de Torquemada\"" [ label = "</film/performance/character>" ];
+	"_:subject1" -> "\"object1\"" [ label = "<http://an.example/predicate1>" ];
+	"<http://example.org/bob#me>" -> "\"1990-07-04\"^^<http://www.w3.org/2001/XMLSchema#date>" [ label = "<http://schema.org/birthDate>" ];
+	"_:subject1" -> "\"some \\\"text\\\"\"" [ label = "<text>" ];
+}
+`,
+	},
+}
+
+func TestWriter(t *testing.T) {
+	buf := bytes.NewBuffer(nil)
+	for _, c := range testData {
+		buf.Reset()
+		w := dot.NewWriter(buf)
+		n, err := quad.Copy(w, quad.NewReader(c.quads))
+		if err != nil {
+			t.Fatalf("write failed after %d quads: %v", n, err)
+		}
+		if err = w.Close(); err != nil {
+			t.Fatal("error on close:", err)
+		}
+		if c.data != buf.String() {
+			t.Fatalf("wrong output:\n%s\n\nvs\n\n%s", buf.String(), c.data)
+		}
+	}
+}