README
¶
nquads
A basic nquads parser in Go
Overview
N-Quads is a serialisation format for RDF datasets. A dataset consists of a default graph with no name and zero or more named graphs where a graph is a composed of a set of triples. The default graph may be empty.
An N-Quads file is a line-oriented format where each triple or quad statement is terminated by a period ..
- IRIs are enclosed by
<and> - Literals have a lexical value enclosed by
"followed by an optional language tag using@as a delimiter, or a data type IRI using^^as a delimiter - Blank nodes have a lexical label prefixed by
_:and the same label denotes the same blank node throughout the file.
A triple in a named graph may be written as a statement using four terms, the last of which is the name of the graph:
<http://example/s> <http://example/p> <http://example/o> <http://example/g> .
A triple in the default graph omits the fourth term:
<http://example/s> <http://example/p> <http://example/o> .
Getting Started
Example of parsing an nquads file and printing out every 5000th quad
package main
import (
"fmt"
"os"
"github.com/iand/nquads"
)
func main() {
nqfile, err := os.Open("myquads.nq")
if err != nil {
fmt.Fprintf(os.Stderr, "Error: %s", err.Error())
os.Exit(1)
}
defer nqfile.Close()
count := 0
r := nquads.NewReader(nqfile)
for r.Next()
count++
if count % 5000 == 0{
fmt.Printf("%s\n", r.Quad())
}
}
if r.Err() != nil {
fmt.Printf("Unexpected error encountered: %v\n", r.Err())
}
}
Author
License
This is free and unencumbered software released into the public domain. For more
information, see http://unlicense.org/ or the accompanying UNLICENSE file.
Credits
The design and logic is inspired by Go's standard csv parsing library
Documentation
¶
Overview ¶
Package nquads parses N-Quads (https://www.w3.org/TR/n-quads/)
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( // ErrUnexpectedCharacter is the error returned when a general syntax error is encountered. ErrUnexpectedCharacter = errors.New("unexpected character") // ErrInvalidCodepointExpression is the error returned when an IRI or literal is encountered with an invalid // unicode encoding of the form \Uxxxxxxxx or \uxxxx is encountered. ErrInvalidCodepointExpression = errors.New("invalid unicode codepoint expression") // ErrUnexpectedEOF is the error returned when an EOF was encountered while reading a quad. ErrUnexpectedEOF = io.ErrUnexpectedEOF // ErrUnterminatedQuad is the error returned when a quad appears to be missing the final period. ErrUnterminatedQuad = errors.New("unterminated quad, expecting '.'") // ErrRelativeIRI is the error returned when a relative IRI is encountered. All IRIs in an N-Quads document must // be written as absolute IRIs. ErrRelativeIRI = errors.New("relative IRI") )
These are the errors that can be returned in ParseError.Error
Functions ¶
This section is empty.
Types ¶
type ParseError ¶
type ParseError struct {
Line int // Line where the error occurred
Column int // Column (rune index) where the error occurred
Err error // The actual error
}
A ParseError is returned for parsing errors. The first line is 1. The first column is 0.
func (*ParseError) Error ¶
func (e *ParseError) Error() string
func (*ParseError) Unwrap ¶
func (e *ParseError) Unwrap() error
type Quad ¶
type Quad struct {
S rdf.Term
P rdf.Term
O rdf.Term
G rdf.Term
}
A Quad consists of a subject, predicate, object and graph
type Reader ¶
type Reader struct {
// contains filtered or unexported fields
}
func (*Reader) Err ¶
Err returns any error encountered while reading. If Err is non-nil then Next will always return false.
Source Files