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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
 
// Package csv reads and writes comma-separated values (CSV) files.
//
// A csv file contains zero or more records of one or more fields per record.
// Each record is separated by the newline character. The final record may
// optionally be followed by a newline character.
//
//      field1,field2,field3
//
// White space is considered part of a field.
//
// Carriage returns before newline characters are silently removed.
//
// Blank lines are ignored.  A line with only whitespace characters (excluding
// the ending newline character) is not considered a blank line.
//
// Fields which start and stop with the quote character " are called
// quoted-fields.  The beginning and ending quote are not part of the
// field.
//
// The source:
//
//      normal string,"quoted-field"
//
// results in the fields
//
//      {`normal string`, `quoted-field`}
//
// Within a quoted-field a quote character followed by a second quote
// character is considered a single quote.
//
//      "the ""word"" is true","a ""quoted-field"""
//
// results in
//
//      {`the "word" is true`, `a "quoted-field"`}
//
// Newlines and commas may be included in a quoted-field
//
//      "Multi-line
//      field","comma is ,"
//
// results in
//
//      {`Multi-line
//      field`, `comma is ,`}
package csv
 
import (
        "bufio"
        "bytes"
        "errors"
        "fmt"
        "io"
        "unicode"
)
 
// A ParseError is returned for parsing errors.
// The first line is 1.  The first column is 0.
type ParseError struct {
        Line   int   // Line where the error occurred
        Column int   // Column (rune index) where the error occurred
        Err    error // The actual error
}
 
func (e *ParseError) Error() string {
        return fmt.Sprintf("line %d, column %d: %s", e.Line, e.Column, e.Err)
}
 
// These are the errors that can be returned in ParseError.Error
var (
        ErrTrailingComma = errors.New("extra delimiter at end of line")
        ErrBareQuote     = errors.New("bare \" in non-quoted-field")
        ErrQuote         = errors.New("extraneous \" in field")
        ErrFieldCount    = errors.New("wrong number of fields in line")
)
 
// A Reader reads records from a CSV-encoded file.
//
// As returned by NewReader, a Reader expects input conforming to RFC 4180.
// The exported fields can be changed to customize the details before the
// first call to Read or ReadAll.
//
// Comma is the field delimiter.  It defaults to ','.
//
// Comment, if not 0, is the comment character. Lines beginning with the
// Comment character are ignored.
//
// If FieldsPerRecord is positive, Read requires each record to
// have the given number of fields.  If FieldsPerRecord is 0, Read sets it to
// the number of fields in the first record, so that future records must
// have the same field count.
//
// If LazyQuotes is true, a quote may appear in an unquoted field and a
// non-doubled quote may appear in a quoted field.
//
// If TrailingComma is true, the last field may be an unquoted empty field.
//
// If TrimLeadingSpace is true, leading white space in a field is ignored.
type Reader struct {
        Comma            rune // Field delimiter (set to ',' by NewReader)
        Comment          rune // Comment character for start of line
        FieldsPerRecord  int  // Number of expected fields per record
        LazyQuotes       bool // Allow lazy quotes
        TrailingComma    bool // Allow trailing comma
        TrimLeadingSpace bool // Trim leading space
        line             int
        column           int
        r                *bufio.Reader
        field            bytes.Buffer
}
 
// NewReader returns a new Reader that reads from r.
func NewReader(r io.Reader) *Reader {
        return &Reader{
                Comma: ',',
                r:     bufio.NewReader(r),
        }
}
 
// error creates a new ParseError based on err.
func (r *Reader) error(err error) error {
        return &ParseError{
                Line:   r.line,
                Column: r.column,
                Err:    err,
        }
}
 
// Read reads one record from r.  The record is a slice of strings with each
// string representing one field.
func (r *Reader) Read() (record []string, err error) {
        for {
                record, err = r.parseRecord()
                if record != nil {
                        break
                }
                if err != nil {
                        return nil, err
                }
        }
 
        if r.FieldsPerRecord > 0 {
                if len(record) != r.FieldsPerRecord {
                        r.column = 0 // report at start of record
                        return record, r.error(ErrFieldCount)
                }
        } else if r.FieldsPerRecord == 0 {
                r.FieldsPerRecord = len(record)
        }
        return record, nil
}
 
// ReadAll reads all the remaining records from r.
// Each record is a slice of fields.
// A successful call returns err == nil, not err == EOF. Because ReadAll is
// defined to read until EOF, it does not treat end of file as an error to be
// reported.
func (r *Reader) ReadAll() (records [][]string, err error) {
        for {
                record, err := r.Read()
                if err == io.EOF {
                        return records, nil
                }
                if err != nil {
                        return nil, err
                }
                records = append(records, record)
        }
        panic("unreachable")
}
 
// readRune reads one rune from r, folding \r\n to \n and keeping track
// of how far into the line we have read.  r.column will point to the start
// of this rune, not the end of this rune.
func (r *Reader) readRune() (rune, error) {
        r1, _, err := r.r.ReadRune()
 
        // Handle \r\n here.  We make the simplifying assumption that
        // anytime \r is followed by \n that it can be folded to \n.
        // We will not detect files which contain both \r\n and bare \n.
        if r1 == '\r' {
                r1, _, err = r.r.ReadRune()
                if err == nil {
                        if r1 != '\n' {
                                r.r.UnreadRune()
                                r1 = '\r'
                        }
                }
        }
        r.column++
        return r1, err
}
 
// unreadRune puts the last rune read from r back.
func (r *Reader) unreadRune() {
        r.r.UnreadRune()
        r.column--
}
 
// skip reads runes up to and including the rune delim or until error.
func (r *Reader) skip(delim rune) error {
        for {
                r1, err := r.readRune()
                if err != nil {
                        return err
                }
                if r1 == delim {
                        return nil
                }
        }
        panic("unreachable")
}
 
// parseRecord reads and parses a single csv record from r.
func (r *Reader) parseRecord() (fields []string, err error) {
        // Each record starts on a new line.  We increment our line
        // number (lines start at 1, not 0) and set column to -1
        // so as we increment in readRune it points to the character we read.
        r.line++
        r.column = -1
 
        // Peek at the first rune.  If it is an error we are done.
        // If we are support comments and it is the comment character
        // then skip to the end of line.
 
        r1, _, err := r.r.ReadRune()
        if err != nil {
                return nil, err
        }
 
        if r.Comment != 0 && r1 == r.Comment {
                return nil, r.skip('\n')
        }
        r.r.UnreadRune()
 
        // At this point we have at least one field.
        for {
                haveField, delim, err := r.parseField()
                if haveField {
                        fields = append(fields, r.field.String())
                }
                if delim == '\n' || err == io.EOF {
                        return fields, err
                } else if err != nil {
                        return nil, err
                }
        }
        panic("unreachable")
}
 
// parseField parses the next field in the record.  The read field is
// located in r.field.  Delim is the first character not part of the field
// (r.Comma or '\n').
func (r *Reader) parseField() (haveField bool, delim rune, err error) {
        r.field.Reset()
 
        r1, err := r.readRune()
        if err != nil {
                // If we have EOF and are not at the start of a line
                // then we return the empty field.  We have already
                // checked for trailing commas if needed.
                if err == io.EOF && r.column != 0 {
                        return true, 0, err
                }
                return false, 0, err
        }
 
        if r.TrimLeadingSpace {
                for r1 != '\n' && unicode.IsSpace(r1) {
                        r1, err = r.readRune()
                        if err != nil {
                                return false, 0, err
                        }
                }
        }
 
        switch r1 {
        case r.Comma:
                // will check below
 
        case '\n':
                // We are a trailing empty field or a blank line
                if r.column == 0 {
                        return false, r1, nil
                }
                return true, r1, nil
 
        case '"':
                // quoted field
        Quoted:
                for {
                        r1, err = r.readRune()
                        if err != nil {
                                if err == io.EOF {
                                        if r.LazyQuotes {
                                                return true, 0, err
                                        }
                                        return false, 0, r.error(ErrQuote)
                                }
                                return false, 0, err
                        }
                        switch r1 {
                        case '"':
                                r1, err = r.readRune()
                                if err != nil || r1 == r.Comma {
                                        break Quoted
                                }
                                if r1 == '\n' {
                                        return true, r1, nil
                                }
                                if r1 != '"' {
                                        if !r.LazyQuotes {
                                                r.column--
                                                return false, 0, r.error(ErrQuote)
                                        }
                                        // accept the bare quote
                                        r.field.WriteRune('"')
                                }
                        case '\n':
                                r.line++
                                r.column = -1
                        }
                        r.field.WriteRune(r1)
                }
 
        default:
                // unquoted field
                for {
                        r.field.WriteRune(r1)
                        r1, err = r.readRune()
                        if err != nil || r1 == r.Comma {
                                break
                        }
                        if r1 == '\n' {
                                return true, r1, nil
                        }
                        if !r.LazyQuotes && r1 == '"' {
                                return false, 0, r.error(ErrBareQuote)
                        }
                }
        }
 
        if err != nil {
                if err == io.EOF {
                        return true, 0, err
                }
                return false, 0, err
        }
 
        if !r.TrailingComma {
                // We don't allow trailing commas.  See if we
                // are at the end of the line (being mindful
                // of trimming spaces).
                c := r.column
                r1, err = r.readRune()
                if r.TrimLeadingSpace {
                        for r1 != '\n' && unicode.IsSpace(r1) {
                                r1, err = r.readRune()
                                if err != nil {
                                        break
                                }
                        }
                }
                if err == io.EOF || r1 == '\n' {
                        r.column = c // report the comma
                        return false, 0, r.error(ErrTrailingComma)
                }
                r.unreadRune()
        }
        return true, r1, nil
}

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Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [encoding/] [csv/] [reader.go] - Blame information for rev 747

Line No.	Rev	Author	Line
1	747	jeremybenn	`// Copyright 2011 The Go Authors. All rights reserved.`
2			`// Use of this source code is governed by a BSD-style`
3			`// license that can be found in the LICENSE file.`
4
5			`// Package csv reads and writes comma-separated values (CSV) files.`
6			`//`
7			`// A csv file contains zero or more records of one or more fields per record.`
8			`// Each record is separated by the newline character. The final record may`
9			`// optionally be followed by a newline character.`
10			`//`
11			`// field1,field2,field3`
12			`//`
13			`// White space is considered part of a field.`
14			`//`
15			`// Carriage returns before newline characters are silently removed.`
16			`//`
17			`// Blank lines are ignored. A line with only whitespace characters (excluding`
18			`// the ending newline character) is not considered a blank line.`
19			`//`
20			`// Fields which start and stop with the quote character " are called`
21			`// quoted-fields. The beginning and ending quote are not part of the`
22			`// field.`
23			`//`
24			`// The source:`
25			`//`
26			`// normal string,"quoted-field"`
27			`//`
28			`// results in the fields`
29			`//`
30			// {`normal string`, `quoted-field`}
31			`//`
32			`// Within a quoted-field a quote character followed by a second quote`
33			`// character is considered a single quote.`
34			`//`
35			`// "the ""word"" is true","a ""quoted-field"""`
36			`//`
37			`// results in`
38			`//`
39			// {`the "word" is true`, `a "quoted-field"`}
40			`//`
41			`// Newlines and commas may be included in a quoted-field`
42			`//`
43			`// "Multi-line`
44			`// field","comma is ,"`
45			`//`
46			`// results in`
47			`//`
48			// {`Multi-line
49			// field`, `comma is ,`}
50			`package csv`
51
52			`import (`
53			`"bufio"`
54			`"bytes"`
55			`"errors"`
56			`"fmt"`
57			`"io"`
58			`"unicode"`
59			`)`
60
61			`// A ParseError is returned for parsing errors.`
62			`// The first line is 1. The first column is 0.`
63			`type ParseError struct {`
64			`Line int // Line where the error occurred`
65			`Column int // Column (rune index) where the error occurred`
66			`Err error // The actual error`
67			`}`
68
69			`func (e *ParseError) Error() string {`
70			`return fmt.Sprintf("line %d, column %d: %s", e.Line, e.Column, e.Err)`
71			`}`
72
73			`// These are the errors that can be returned in ParseError.Error`
74			`var (`
75			`ErrTrailingComma = errors.New("extra delimiter at end of line")`
76			`ErrBareQuote = errors.New("bare \" in non-quoted-field")`
77			`ErrQuote = errors.New("extraneous \" in field")`
78			`ErrFieldCount = errors.New("wrong number of fields in line")`
79			`)`
80
81			`// A Reader reads records from a CSV-encoded file.`
82			`//`
83			`// As returned by NewReader, a Reader expects input conforming to RFC 4180.`
84			`// The exported fields can be changed to customize the details before the`
85			`// first call to Read or ReadAll.`
86			`//`
87			`// Comma is the field delimiter. It defaults to ','.`
88			`//`
89			`// Comment, if not 0, is the comment character. Lines beginning with the`
90			`// Comment character are ignored.`
91			`//`
92			`// If FieldsPerRecord is positive, Read requires each record to`
93			`// have the given number of fields. If FieldsPerRecord is 0, Read sets it to`
94			`// the number of fields in the first record, so that future records must`
95			`// have the same field count.`
96			`//`
97			`// If LazyQuotes is true, a quote may appear in an unquoted field and a`
98			`// non-doubled quote may appear in a quoted field.`
99			`//`
100			`// If TrailingComma is true, the last field may be an unquoted empty field.`
101			`//`
102			`// If TrimLeadingSpace is true, leading white space in a field is ignored.`
103			`type Reader struct {`
104			`Comma rune // Field delimiter (set to ',' by NewReader)`
105			`Comment rune // Comment character for start of line`
106			`FieldsPerRecord int // Number of expected fields per record`
107			`LazyQuotes bool // Allow lazy quotes`
108			`TrailingComma bool // Allow trailing comma`
109			`TrimLeadingSpace bool // Trim leading space`
110			`line int`
111			`column int`
112			`r *bufio.Reader`
113			`field bytes.Buffer`
114			`}`
115
116			`// NewReader returns a new Reader that reads from r.`
117			`func NewReader(r io.Reader) *Reader {`
118			`return &Reader{`
119			`Comma: ',',`
120			`r: bufio.NewReader(r),`
121			`}`
122			`}`
123
124			`// error creates a new ParseError based on err.`
125			`func (r *Reader) error(err error) error {`
126			`return &ParseError{`
127			`Line: r.line,`
128			`Column: r.column,`
129			`Err: err,`
130			`}`
131			`}`
132
133			`// Read reads one record from r. The record is a slice of strings with each`
134			`// string representing one field.`
135			`func (r *Reader) Read() (record []string, err error) {`
136			`for {`
137			`record, err = r.parseRecord()`
138			`if record != nil {`
139			`break`
140			`}`
141			`if err != nil {`
142			`return nil, err`
143			`}`
144			`}`
145
146			`if r.FieldsPerRecord > 0 {`
147			`if len(record) != r.FieldsPerRecord {`
148			`r.column = 0 // report at start of record`
149			`return record, r.error(ErrFieldCount)`
150			`}`
151			`} else if r.FieldsPerRecord == 0 {`
152			`r.FieldsPerRecord = len(record)`
153			`}`
154			`return record, nil`
155			`}`
156
157			`// ReadAll reads all the remaining records from r.`
158			`// Each record is a slice of fields.`
159			`// A successful call returns err == nil, not err == EOF. Because ReadAll is`
160			`// defined to read until EOF, it does not treat end of file as an error to be`
161			`// reported.`
162			`func (r *Reader) ReadAll() (records [][]string, err error) {`
163			`for {`
164			`record, err := r.Read()`
165			`if err == io.EOF {`
166			`return records, nil`
167			`}`
168			`if err != nil {`
169			`return nil, err`
170			`}`
171			`records = append(records, record)`
172			`}`
173			`panic("unreachable")`
174			`}`
175
176			`// readRune reads one rune from r, folding \r\n to \n and keeping track`
177			`// of how far into the line we have read. r.column will point to the start`
178			`// of this rune, not the end of this rune.`
179			`func (r *Reader) readRune() (rune, error) {`
180			`r1, _, err := r.r.ReadRune()`
181
182			`// Handle \r\n here. We make the simplifying assumption that`
183			`// anytime \r is followed by \n that it can be folded to \n.`
184			`// We will not detect files which contain both \r\n and bare \n.`
185			`if r1 == '\r' {`
186			`r1, _, err = r.r.ReadRune()`
187			`if err == nil {`
188			`if r1 != '\n' {`
189			`r.r.UnreadRune()`
190			`r1 = '\r'`
191			`}`
192			`}`
193			`}`
194			`r.column++`
195			`return r1, err`
196			`}`
197
198			`// unreadRune puts the last rune read from r back.`
199			`func (r *Reader) unreadRune() {`
200			`r.r.UnreadRune()`
201			`r.column--`
202			`}`
203
204			`// skip reads runes up to and including the rune delim or until error.`
205			`func (r *Reader) skip(delim rune) error {`
206			`for {`
207			`r1, err := r.readRune()`
208			`if err != nil {`
209			`return err`
210			`}`
211			`if r1 == delim {`
212			`return nil`
213			`}`
214			`}`
215			`panic("unreachable")`
216			`}`
217
218			`// parseRecord reads and parses a single csv record from r.`
219			`func (r *Reader) parseRecord() (fields []string, err error) {`
220			`// Each record starts on a new line. We increment our line`
221			`// number (lines start at 1, not 0) and set column to -1`
222			`// so as we increment in readRune it points to the character we read.`
223			`r.line++`
224			`r.column = -1`
225
226			`// Peek at the first rune. If it is an error we are done.`
227			`// If we are support comments and it is the comment character`
228			`// then skip to the end of line.`
229
230			`r1, _, err := r.r.ReadRune()`
231			`if err != nil {`
232			`return nil, err`
233			`}`
234
235			`if r.Comment != 0 && r1 == r.Comment {`
236			`return nil, r.skip('\n')`
237			`}`
238			`r.r.UnreadRune()`
239
240			`// At this point we have at least one field.`
241			`for {`
242			`haveField, delim, err := r.parseField()`
243			`if haveField {`
244			`fields = append(fields, r.field.String())`
245			`}`
246			`if delim == '\n' \|\| err == io.EOF {`
247			`return fields, err`
248			`} else if err != nil {`
249			`return nil, err`
250			`}`
251			`}`
252			`panic("unreachable")`
253			`}`
254
255			`// parseField parses the next field in the record. The read field is`
256			`// located in r.field. Delim is the first character not part of the field`
257			`// (r.Comma or '\n').`
258			`func (r *Reader) parseField() (haveField bool, delim rune, err error) {`
259			`r.field.Reset()`
260
261			`r1, err := r.readRune()`
262			`if err != nil {`
263			`// If we have EOF and are not at the start of a line`
264			`// then we return the empty field. We have already`
265			`// checked for trailing commas if needed.`
266			`if err == io.EOF && r.column != 0 {`
267			`return true, 0, err`
268			`}`
269			`return false, 0, err`
270			`}`
271
272			`if r.TrimLeadingSpace {`
273			`for r1 != '\n' && unicode.IsSpace(r1) {`
274			`r1, err = r.readRune()`
275			`if err != nil {`
276			`return false, 0, err`
277			`}`
278			`}`
279			`}`
280
281			`switch r1 {`
282			`case r.Comma:`
283			`// will check below`
284
285			`case '\n':`
286			`// We are a trailing empty field or a blank line`
287			`if r.column == 0 {`
288			`return false, r1, nil`
289			`}`
290			`return true, r1, nil`
291
292			`case '"':`
293			`// quoted field`
294			`Quoted:`
295			`for {`
296			`r1, err = r.readRune()`
297			`if err != nil {`
298			`if err == io.EOF {`
299			`if r.LazyQuotes {`
300			`return true, 0, err`
301			`}`
302			`return false, 0, r.error(ErrQuote)`
303			`}`
304			`return false, 0, err`
305			`}`
306			`switch r1 {`
307			`case '"':`
308			`r1, err = r.readRune()`
309			`if err != nil \|\| r1 == r.Comma {`
310			`break Quoted`
311			`}`
312			`if r1 == '\n' {`
313			`return true, r1, nil`
314			`}`
315			`if r1 != '"' {`
316			`if !r.LazyQuotes {`
317			`r.column--`
318			`return false, 0, r.error(ErrQuote)`
319			`}`
320			`// accept the bare quote`
321			`r.field.WriteRune('"')`
322			`}`
323			`case '\n':`
324			`r.line++`
325			`r.column = -1`
326			`}`
327			`r.field.WriteRune(r1)`
328			`}`
329
330			`default:`
331			`// unquoted field`
332			`for {`
333			`r.field.WriteRune(r1)`
334			`r1, err = r.readRune()`
335			`if err != nil \|\| r1 == r.Comma {`
336			`break`
337			`}`
338			`if r1 == '\n' {`
339			`return true, r1, nil`
340			`}`
341			`if !r.LazyQuotes && r1 == '"' {`
342			`return false, 0, r.error(ErrBareQuote)`
343			`}`
344			`}`
345			`}`
346
347			`if err != nil {`
348			`if err == io.EOF {`
349			`return true, 0, err`
350			`}`
351			`return false, 0, err`
352			`}`
353
354			`if !r.TrailingComma {`
355			`// We don't allow trailing commas. See if we`
356			`// are at the end of the line (being mindful`
357			`// of trimming spaces).`
358			`c := r.column`
359			`r1, err = r.readRune()`
360			`if r.TrimLeadingSpace {`
361			`for r1 != '\n' && unicode.IsSpace(r1) {`
362			`r1, err = r.readRune()`
363			`if err != nil {`
364			`break`
365			`}`
366			`}`
367			`}`
368			`if err == io.EOF \|\| r1 == '\n' {`
369			`r.column = c // report the comma`
370			`return false, 0, r.error(ErrTrailingComma)`
371			`}`
372			`r.unreadRune()`
373			`}`
374			`return true, r1, nil`
375			`}`