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qgsdelimitedtextfile.cpp
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qgsdelimitedtextfile.cpp
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/***************************************************************************
qgsdelimitedtextfile.cpp - Data provider for delimted text
-------------------
begin : 2012-01-20
copyright : (C) 201 by Chris Crook
email : ccrook at linz.govt.nz
***************************************************************************/
/***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#include "qgsdelimitedtextfile.h"
#include "qgslogger.h"
#include <QtGlobal>
#include <QFile>
#include <QDataStream>
#include <QTextStream>
#include <QTextCodec>
#include <QStringList>
#include <QRegExp>
#include <QUrl>
static QString DefaultFieldName( "field_%1" );
static QRegExp InvalidFieldRegexp( "^\\d*(\\.\\d*)?$" );
// field_ is optional in following regexp to simplify QgsDelimitedTextFile::fieldNumber()
static QRegExp DefaultFieldRegexp( "^(?:field_)?(\\d+)$", Qt::CaseInsensitive );
QgsDelimitedTextFile::QgsDelimitedTextFile( QString url ) :
mFileName( QString() ),
mEncoding( "UTF-8" ),
mFile( 0 ),
mStream( 0 ),
mDefinitionValid( false ),
mUseHeader( true ),
mDiscardEmptyFields( false ),
mTrimFields( false ),
mSkipLines( 0 ),
mMaxFields( 0 ),
mLineNumber( 0 ),
mRecordLineNumber( 0 ),
mMaxFieldCount( 0 )
{
// The default type is CSV
setTypeCSV();
if ( ! url.isNull() ) setFromUrl( url );
}
QgsDelimitedTextFile::~QgsDelimitedTextFile()
{
close();
}
void QgsDelimitedTextFile::close()
{
if ( mStream )
{
delete mStream;
mStream = 0;
}
if ( mFile )
{
delete mFile;
mFile = 0;
}
}
bool QgsDelimitedTextFile::open()
{
if ( ! mFile )
{
close();
mFile = new QFile( mFileName );
if ( ! mFile->open( QIODevice::ReadOnly ) )
{
QgsDebugMsg( "Data file " + mFileName + " could not be opened" );
delete mFile;
mFile = 0;
return false;
}
mStream = new QTextStream( mFile );
if ( ! mEncoding.isEmpty() )
{
QTextCodec *codec = QTextCodec::codecForName( mEncoding.toAscii() );
mStream->setCodec( codec );
}
}
return true;
}
// Clear information based on current definition of file
void QgsDelimitedTextFile::resetDefinition()
{
close();
mFieldNames.clear();
mMaxFieldCount = 0;
}
// Extract the provider definition from the url
bool QgsDelimitedTextFile::setFromUrl( QString url )
{
QUrl qurl = QUrl::fromEncoded( url.toAscii() );
return setFromUrl( qurl );
}
// Extract the provider definition from the url
bool QgsDelimitedTextFile::setFromUrl( QUrl &url )
{
// Close any existing definition
resetDefinition();
// Extract the file name
setFileName( url.toLocalFile() );
// Extract the encoding
if ( url.hasQueryItem( "encoding" ) )
{
mEncoding = url.queryItemValue( "encoding" );
}
// The default type is csv, to be consistent with the
// previous implementation (except that quoting should be handled properly)
QString type( "csv" );
QString delimiter( "," );
QString quote = "\"";
QString escape = "\"";
mUseHeader = true;
mSkipLines = 0;
// Prefer simple "type" for delimiter type, but include delimiterType
// as optional name for backwards compatibility
if ( url.hasQueryItem( "type" ) || url.hasQueryItem( "delimiterType" ) )
{
if ( url.hasQueryItem( "type" ) )
type = url.queryItemValue( "type" );
else if ( url.hasQueryItem( "delimiterType" ) )
type = url.queryItemValue( "delimiterType" );
// Support for previous version of Qgs - plain chars had
// quote characters ' or "
if ( type == "plain" )
{
quote = "'\"";
escape = "";
}
}
if ( url.hasQueryItem( "delimiter" ) )
{
delimiter = url.queryItemValue( "delimiter" );
}
if ( url.hasQueryItem( "quote" ) )
{
quote = url.queryItemValue( "quote" );
}
if ( url.hasQueryItem( "escape" ) )
{
escape = url.queryItemValue( "escape" );
}
if ( url.hasQueryItem( "skipLines" ) )
{
mSkipLines = url.queryItemValue( "skipLines" ).toInt();
}
if ( url.hasQueryItem( "useHeader" ) )
{
mUseHeader = ! url.queryItemValue( "useHeader" ).toUpper().startsWith( 'N' );
}
if ( url.hasQueryItem( "skipEmptyFields" ) )
{
mDiscardEmptyFields = ! url.queryItemValue( "useHeader" ).toUpper().startsWith( 'N' );;
}
if ( url.hasQueryItem( "trimFields" ) )
{
mTrimFields = ! url.queryItemValue( "trimFields" ).toUpper().startsWith( 'N' );;
}
if ( url.hasQueryItem( "maxFields" ) )
{
mMaxFields = url.queryItemValue( "maxFields" ).toInt();
}
QgsDebugMsg( "Delimited text file is: " + mFileName );
QgsDebugMsg( "Encoding is: " + mEncoding );
QgsDebugMsg( "Delimited file type is: " + type );
QgsDebugMsg( "Delimiter is: [" + delimiter + "]" );
QgsDebugMsg( "Quote character is: [" + quote + "]" );
QgsDebugMsg( "Escape character is: [" + escape + "]" );
QgsDebugMsg( "Skip lines: " + QString::number( mSkipLines ) );
QgsDebugMsg( "Maximum number of fields in record: " + QString::number( mMaxFields ) );
QgsDebugMsg( "Use headers: " + QString( mUseHeader ? "Yes" : "No" ) );
QgsDebugMsg( "Discard empty fields: " + QString( mDiscardEmptyFields ? "Yes" : "No" ) );
QgsDebugMsg( "Trim fields: " + QString( mTrimFields ? "Yes" : "No" ) );
// Support for previous version of plain characters
if ( type == "csv" || type == "plain" )
{
setTypeCSV( delimiter, quote, escape );
}
else if ( type == "whitespace" )
{
setTypeWhitespace();
}
else if ( type == "regexp" )
{
setTypeRegexp( delimiter );
}
else
{
return false;
}
return mDefinitionValid;
}
QUrl QgsDelimitedTextFile::url()
{
QUrl url = QUrl::fromLocalFile( mFileName );
if ( mEncoding != "UTF-8" )
{
url.addQueryItem( "encoding", mEncoding );
}
url.addQueryItem( "type", type() );
if ( mType == DelimTypeRegexp )
{
url.addQueryItem( "delimiter", mDelimRegexp.pattern() );
}
if ( mType == DelimTypeCSV )
{
if ( mDelimChars != "," ) url.addQueryItem( "delimiter", encodeChars( mDelimChars ) );
if ( mQuoteChar != "\"" ) url.addQueryItem( "quote", encodeChars( mQuoteChar ) );
if ( mEscapeChar != "\"" ) url.addQueryItem( "escape", encodeChars( mEscapeChar ) );
}
if ( mSkipLines > 0 )
{
url.addQueryItem( "skipLines", QString::number( mSkipLines ) );
}
if ( ! mUseHeader )
{
url.addQueryItem( "useHeader", "No" );
}
if ( mTrimFields )
{
url.addQueryItem( "trimFields", "Yes" );
}
if ( mDiscardEmptyFields && mType != DelimTypeWhitespace )
{
url.addQueryItem( "skipEmptyFields", "Yes" );
}
if ( mMaxFields > 0 )
{
url.addQueryItem( "maxFields", QString::number( mMaxFields ) );
}
return url;
}
void QgsDelimitedTextFile::setFileName( QString filename )
{
resetDefinition();
mFileName = filename;
}
void QgsDelimitedTextFile::setEncoding( QString encoding )
{
resetDefinition();
mEncoding = encoding;
}
QString QgsDelimitedTextFile::type()
{
if ( mType == DelimTypeWhitespace ) return QString( "whitespace" );
if ( mType == DelimTypeCSV ) return QString( "csv" );
if ( mType == DelimTypeRegexp ) return QString( "regexp" );
return QString( "csv" );
}
void QgsDelimitedTextFile::setTypeWhitespace()
{
setTypeRegexp( "\\s+" );
mDiscardEmptyFields = true;
mType = DelimTypeWhitespace;
}
void QgsDelimitedTextFile::setTypeRegexp( QString regexp )
{
resetDefinition();
mType = DelimTypeRegexp;
mDelimRegexp.setPattern( regexp );
mAnchoredRegexp = regexp.startsWith( "^" );
mParser = &QgsDelimitedTextFile::parseRegexp;
mDefinitionValid = regexp.size() > 0 && mDelimRegexp.isValid();
if ( ! mDefinitionValid )
{
QgsDebugMsg( "Invalid regular expression in delimited text file delimiter: " + regexp );
}
else if ( mAnchoredRegexp && mDelimRegexp.captureCount() == 0 )
{
mDefinitionValid = false;
QgsDebugMsg( "Invalid anchored regular expression - must have capture groups: " + regexp );
}
}
QString QgsDelimitedTextFile::decodeChars( QString chars )
{
chars = chars.replace( "\\t", "\t" );
return chars;
}
QString QgsDelimitedTextFile::encodeChars( QString chars )
{
chars = chars.replace( "\t", "\\t" );
return chars;
}
void QgsDelimitedTextFile::setTypeCSV( QString delim, QString quote, QString escape )
{
resetDefinition();
mType = DelimTypeRegexp;
mType = DelimTypeCSV;
mDelimChars = decodeChars( delim );
mQuoteChar = decodeChars( quote );
mEscapeChar = decodeChars( escape );
mParser = &QgsDelimitedTextFile::parseQuoted;
mDefinitionValid = mDelimChars.size() > 0;
if ( ! mDefinitionValid )
{
QgsDebugMsg( "Invalid empty delimiter defined for text file delimiter" );
}
}
void QgsDelimitedTextFile::setSkipLines( int skiplines )
{
resetDefinition();
mSkipLines = skiplines;
}
void QgsDelimitedTextFile::setUseHeader( bool useheader )
{
resetDefinition();
mUseHeader = useheader;
}
void QgsDelimitedTextFile::setTrimFields( bool trimFields )
{
resetDefinition();
mTrimFields = trimFields;
}
void QgsDelimitedTextFile::setMaxFields( int maxFields )
{
resetDefinition();
mMaxFields = maxFields;
}
void QgsDelimitedTextFile::setDiscardEmptyFields( bool discardEmptyFields )
{
resetDefinition();
mDiscardEmptyFields = discardEmptyFields;
}
void QgsDelimitedTextFile::setFieldNames( const QStringList &names )
{
mFieldNames.empty();
foreach ( QString name, names )
{
bool nameOk = true;
int fieldNo = mFieldNames.size() + 1;
name = name.trimmed();
// If the name is invalid then reset it to default name
if ( InvalidFieldRegexp.exactMatch( name ) )
{
name = DefaultFieldName.arg( fieldNo );
}
// If the name looks like a default field name (field_##), then it is
// valid if the number matches its column number..
else if ( DefaultFieldRegexp.indexIn( name ) == 0 )
{
int col = DefaultFieldRegexp.capturedTexts()[1].toInt();
nameOk = col == fieldNo;
}
// Otherwise it is valid if isn't the name of an existing field...
else
{
nameOk = ! mFieldNames.contains( name, Qt::CaseInsensitive );
}
// If it is not a valid name then try appending a number to generate
// a valid name.
if ( ! nameOk )
{
int suffix = 0;
QString basename = name + "_%1";
while ( true )
{
suffix++;
name = basename.arg( suffix );
// Not ok if it is already in the name list
if ( mFieldNames.contains( name, Qt::CaseInsensitive ) ) continue;
// Not ok if it is already in proposed names
if ( names.contains( name, Qt::CaseInsensitive ) ) continue;
break;
}
}
mFieldNames.append( name );
}
}
QStringList &QgsDelimitedTextFile::fieldNames()
{
// If not yet opened then reset file to read column headers
//
if ( mUseHeader && ! mFile ) reset();
// If have read more fields than field names, then append field names
// to match the field count (will only happen if parsed some records)
if ( mMaxFieldCount > mFieldNames.size() )
{
for ( int i = mFieldNames.size() + 1; i <= mMaxFieldCount; i++ )
{
mFieldNames.append( DefaultFieldName.arg( i ) );
}
}
return mFieldNames;
}
int QgsDelimitedTextFile::fieldIndex( QString name )
{
// If not yet opened then reset file to read column headers
//
if ( mUseHeader && ! mFile ) reset();
// Try to determine the field based on a default field name, includes
// Field_### and simple integer fields.
if ( DefaultFieldRegexp.indexIn( name ) == 0 )
{
return DefaultFieldRegexp.capturedTexts()[1].toInt() - 1;
}
for ( int i = 0; i < mFieldNames.size(); i++ )
{
if ( mFieldNames[i].compare( name, Qt::CaseInsensitive ) == 0 ) return i;
}
return -1;
}
QgsDelimitedTextFile::Status QgsDelimitedTextFile::nextRecord( QStringList &record )
{
return ( this->*mParser )( record );
}
QgsDelimitedTextFile::Status QgsDelimitedTextFile::reset()
{
// Make sure the file is valid open
if ( ! isValid() || ! open() ) return InvalidDefinition;
// Reset the file pointer
mStream->seek( 0 );
mLineNumber = 0;
mRecordLineNumber = 0;
// Skip header lines
for ( int i = mSkipLines; i-- > 0; )
{
if ( mStream->readLine().isNull() ) return RecordEOF;
mLineNumber++;
}
// Read the column names
if ( mUseHeader )
{
QStringList names;
QgsDelimitedTextFile::Status result = nextRecord( names );
setFieldNames( names );
return result;
}
return RecordOk;
}
QgsDelimitedTextFile::Status QgsDelimitedTextFile::nextLine( QString &buffer, bool skipBlank )
{
if ( ! mStream )
{
Status status = reset();
if ( status != RecordOk ) return status;
}
while ( ! mStream->atEnd() )
{
buffer = mStream->readLine();
if ( buffer.isNull() ) break;
mLineNumber++;
if ( skipBlank && buffer.isEmpty() ) continue;
return RecordOk;
}
// Null string if at end of stream
return RecordEOF;
}
void QgsDelimitedTextFile::appendField( QStringList &record, QString field, bool quoted )
{
if ( mMaxFields > 0 && record.size() >= mMaxFields ) return;
if ( quoted )
{
record.append( field );
}
else
{
if ( mTrimFields ) field = field.trimmed();
if ( !( mDiscardEmptyFields && field.isEmpty() ) ) record.append( field );
}
// Keep track of maximum number of non-empty fields in a record
if ( record.size() > mMaxFieldCount && ! field.isEmpty() ) mMaxFieldCount = record.size();
}
QgsDelimitedTextFile::Status QgsDelimitedTextFile::parseRegexp( QStringList &fields )
{
fields.clear();
QString buffer;
Status status = nextLine( buffer, true );
if ( status != RecordOk ) return status;
mRecordLineNumber = mLineNumber;
// If match is anchored, then only interested in records which actually match
// and extract capture groups
if ( mAnchoredRegexp )
{
if ( mDelimRegexp.indexIn( buffer ) < 0 ) return RecordInvalid;
QStringList groups = mDelimRegexp.capturedTexts();
for ( int i = 1; i < groups.size(); i++ )
{
appendField( fields, groups[i] );
}
return RecordOk;
}
int pos = 0;
int size = buffer.size();
while ( true )
{
if ( pos >= size ) break;
int matchPos = mDelimRegexp.indexIn( buffer, pos );
// If match won't advance cursor, then need to force it along one place
// to avoid infinite loop.
int matchLen = mDelimRegexp.matchedLength();
if ( matchPos == pos && matchLen == 0 )
{
matchPos = mDelimRegexp.indexIn( buffer, pos + 1 );
matchLen = mDelimRegexp.matchedLength();
}
// If no match, then field is to end of record
if ( matchPos < 0 )
{
appendField( fields, buffer.mid( pos ) );
break;
}
// Else append up to matched string, then any capture
// groups from match
appendField( fields, buffer.mid( pos, matchPos - pos ) );
if ( mDelimRegexp.captureCount() > 0 )
{
QStringList groups = mDelimRegexp.capturedTexts();
for ( int i = 1; i < groups.size(); i++ )
{
appendField( fields, groups[i] );
}
}
// Advance the buffer pointer
pos = matchPos + matchLen;
// Quit loop if we have enough fields.
if ( mMaxFields > 0 && fields.size() >= mMaxFields ) break;
}
return RecordOk;
}
QgsDelimitedTextFile::Status QgsDelimitedTextFile::parseQuoted( QStringList &fields )
{
fields.clear();
// Find the first non-blank line to read
QString buffer;
Status status = nextLine( buffer, true );
if ( status != RecordOk ) return status;
mRecordLineNumber = mLineNumber;
QString field; // String in which to accumulate next field
bool escaped = false; // Next char is escaped
bool quoted = false; // In quotes
QChar quoteChar = 0; // Actual quote character used to open quotes
bool started = false; // Non-blank chars in field or quotes started
bool ended = false; // Quoted field ended
int cp = 0; // Pointer to the next character in the buffer
int cpmax = buffer.size(); // End of string
while ( true )
{
QChar c = buffer[cp];
cp++;
// If end of line then if escaped or buffered then try to get more...
if ( cp > cpmax )
{
if ( quoted || escaped )
{
status = nextLine( buffer, false );
if ( status != RecordOk )
{
status = RecordInvalid;
break;
}
field.append( '\n' );
cp = 0;
cpmax = buffer.size();
escaped = false;
continue;
}
break;
}
// If escaped, then just append the character
if ( escaped )
{
field.append( c );
escaped = false;
continue;
}
// Determine if this is a special character - test each class in turn
// Note that delimiters are not valid as quotes or escape character
//
// Somewhat convoluted logic around quote and escape chars is
// to enforce logic for escape characters that are also quote characters.
// These escapes can only escape themselves and only in quotes using them
// as delimiters!
bool isQuote = false;
bool isEscape = false;
bool isDelim = mDelimChars.contains( c );
if ( ! isDelim )
{
bool isQuoteChar = mQuoteChar.contains( c );
isQuote = quoted ? c == quoteChar : isQuoteChar;
isEscape = mEscapeChar.contains( c );
if ( isQuoteChar && isEscape ) isEscape = isQuote;
}
// Start or end of quote ...
if ( isQuote )
{
// quote char in quoted field
if ( quoted )
{
// if is also escape and next character is quote, then
// escape the quote..
if ( isEscape && buffer[cp] == quoteChar )
{
field.append( quoteChar );
cp++;
}
// Otherwise end of quoted field
else
{
quoted = false;
ended = true;
}
}
// quote char at start of field .. start of quoted fields
else if ( ! started )
{
field.clear();
quoteChar = c;
quoted = true;
started = true;
}
// Cannot have a quote embedded in a field
else
{
fields.clear();
return RecordInvalid;
}
}
// If escape char, then next char is escaped...
else if ( isEscape )
{
escaped = true;
}
// If within quotes, then append to the string
else if ( quoted )
{
field.append( c );
}
// If it is a delimiter, then end of field...
else if ( isDelim )
{
appendField( fields, field, ended );
// Clear the field
field.clear();
started = false;
ended = false;
}
// Whitespace is permitted before the start of a field, or
// after the end..
else if ( c.isSpace() )
{
if ( ! ended ) field.append( c );
}
// Other chars permitted if not after quoted field
else
{
if ( ended )
{
fields.clear();
return RecordInvalid;
}
field.append( c );
started = true;
}
}
// If reached the end of the record, then add the last field...
if ( started )
{
appendField( fields, field, ended );
}
return status;
}
bool QgsDelimitedTextFile::isValid()
{
return mDefinitionValid && QFile::exists( mFileName );
}