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++all: 

* DSNLEXER::NextTok() now uses two separate modes to parse quoted strings.
    This gives us the freedom to control our own destiny separate from the
    constraints put on us by the Specctra DSN spec.
  * Added Documentation/s-expressions.txt to explain all this.
  * Enhanced our quoting protocol by moving away from doubling up double quotes
    to a C line escape mechanism.
  * Now support multi-line strings, which when properly escaped, can still be
    read in as a token originating on a single line.
This commit is contained in:
Dick Hollenbeck 2011-01-30 13:26:03 -06:00
parent 73bdd76a5c
commit 604edcac3a
8 changed files with 284 additions and 91 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
CHANGELOG.txt
View File

@ -4,6 +4,18 @@ KiCad ChangeLog 2010
Please add newer entries at the top, list the date and your name with
email address.
2011-Jan-30 UPDATE Dick Hollenbeck <dick@softplc.com>
================================================================================
++all:
* DSNLEXER::NextTok() now uses two separate modes to parse quoted strings.
This gives us the freedom to control our own destiny separate from the
constraints put on us by the Specctra DSN spec.
* Added Documentation/s-expressions.txt to explain all this.
* Enhanced our quoting protocol by moving away from doubling up double quotes
to a C line escape mechanism.
* Now support multi-line strings, which when properly escaped, can still be
read in as a token originating on a single line.
2011-Jan-21 UPDATE Wayne Stambaugh <stambaughw@verizon.net>
================================================================================
EESchema code refactoring and coding policy naming fixes.

89
Documentation/s-expressions.txt Normal file
View File

@ -0,0 +1,89 @@
S-Expression Support in Kicad
============================================================================
Author: Dick Hollenbeck
Date: Jan 2011
An s-expression is a text stream or string, in the same vain as XML, consisting
of a sequence of elements. Each element is either an atom or list. An atom
corresponds to a string, while a list corresponds to an s-expression. The
following grammar represents our definition of an s-expression:
sexpr ::= ( sx )
sx ::= atom sxtail | sexptr sxtail | NULL
sxtail ::= sx | NULL
atom :: quoted | value
quoted :: "ws_string"
value :: nws_string
An atom can either be a quoted string, which is a string containing whitespace
surrounded by double quotes, or a non-whitespace string that does not require
surrounding quotes.
The s-expression syntax used in Kicad uses two quoting/syntax strategies, given
by the needs of the Specctra DSN specification and of our own non-specctra
needs. The Specctra DSN specification is not very clear with regard to quoting
and on top of that there is Freerouter's interpretation, which would actually
supercede anything in the Specctra DSN spec anyway, due to a desire to be
compatible with Freerouter.
We have our own needs, which go beyond those of the Specctra DSN spec, so we
support the two syntaxes or quoting protocols for quoted atoms:
1) Specctra quoting protocol (specctraMode)
2) Kicad quoting protocol (non-specctraMode)
We can control our own destiny better by having a separately defined mode for
non Specctra DSN files.
To summarize, in specctraMode Freerouter dictates to us what we need to do. In
non-specctraMode, which can be thought of as Kicad mode, we have our own quoting
protocol and can make changes without breaking the specctraMode.
There needs to be agreement between how a file is saved, and how a file is read
back in, in either mode, to fulfill the round-tripping requirements. A file
written using one mode may not necessarily be readable using the other mode,
although it might be. Just don't count on it.
In Kicad mode:
OUTPUTFORMATTER::Quoted() is the tool to wrap s-expression atoms.
DSNLEXER::NexTok() is basically the inverse function, and reads tokens back in.
These two must agree, so that what is written out comes back in un-altered.
The decision to wrap the string or not is left to the Quoted() function. If the
string is wrapped, it will also escape internal double quotes, \n's and \r's.
Any null string is wrapped in quotes, and so is any string which starts with
'#', so that it is not confused with an s-expression comment.
Kicad S-expression Syntax and Quoting Protocol (non-specctraMode):
==================================================================
*) All Kicad s-expression files are saved using a UTF8 encoding and should
support any international characters in the atoms. Some atoms are considered
keywords, and constitute a grammar superimposed on the s-expressions.
*) All keywords are ASCII and lowercase. International characters are not to be
used here.
*) DSNLEXER::NextTok() requires that any token be on a single line of input. If
you want to save a multi-line string, Quoted() will automatically escape the \n
or \r for you and put the output on a single line. It should round-trip fine.
*) There can be escape sequences in a quoted string only. Escape sequences allow
foreign tools to generate byte patterns in the input stream. C style 2 byte hex
codes are supported, and so are 3 byte octal escape sequences. See DSNLEXER::NextTok()
for the full list of escape sequences, by searching file dsnlexer.cpp for the
string "ESCAPE SEQUENCES". Any use of the escape mechanism must still produce
UTF-8 encoded text after the escape handling is applied.
*) Just because an escape sequence is supported on input, does not mean that
OUTPUTFORMATTER::Quoted() must generate such an escape sequence for output. For
example, having true tabs in the s-expression file is OK. So that will not be
escaped on output. Other similar cases exist.
*) Backslash is the escape byte.

167
common/dsnlexer.cpp
View File

@ -54,7 +54,8 @@ void DSNLEXER::init()
curTok = DSN_NONE;
stringDelimiter = '"';
space_in_quoted_tokens = true;
specctraMode = false;
space_in_quoted_tokens = false;
commentsAreTokens = false;
}
@ -107,6 +108,20 @@ DSNLEXER::~DSNLEXER()
}
}
void DSNLEXER::SetSpecctraMode( bool aMode )
{
specctraMode = aMode;
if( aMode )
{
// specctra mode defaults, some of which can still be changed in this mode.
space_in_quoted_tokens = true;
}
else
{
space_in_quoted_tokens = false;
stringDelimiter = '"';
}
}
void DSNLEXER::PushReader( LINE_READER* aLineReader )
{
@ -479,74 +494,119 @@ L_read:
// else it was something like +5V, fall through below
}
// a quoted string
// a quoted string, will return DSN_STRING
if( *cur == stringDelimiter )
{
// New code, understands nested quotes, and deliberately restricts
// strings to a single line. Still strips off leading and trailing
// quotes, and now removes internal doubled up quotes
#if 1
head = cur;
// copy the token, character by character so we can remove doubled up quotes.
curText.clear();
while( head < limit )
// Non-specctraMode, understands and deciphers escaped \, \r, \n, and \".
// Strips off leading and trailing double quotes
if( !specctraMode )
{
if( *head==stringDelimiter )
// copy the token, character by character so we can remove doubled up quotes.
curText.clear();
++cur; // skip over the leading delimiter, which is always " in non-specctraMode
head = cur;
while( head<limit )
{
if( head+1<limit && head[1]==stringDelimiter )
// ESCAPE SEQUENCES:
if( *head =='\\' )
{
// include only one of the doubled-up stringDelimiters
curText += *head;
head += 2;
continue;
}
else if( head == cur )
{
++head; // skip the leading quote
continue;
char tbuf[8];
char c;
int i;
if( ++head >= limit )
break; // throw exception at L_unterminated
switch( *head++ )
{
case '"':
case '\\': c = head[-1]; break;
case 'a': c = '\x07'; break;
case 'b': c = '\x08'; break;
case 'f': c = '\x0c'; break;
case 'n': c = '\n'; break;
case 'r': c = '\r'; break;
case 't': c = '\x09'; break;
case 'v': c = '\x0b'; break;
case 'x': // 1 or 2 byte hex escape sequence
for( i=0; i<2; ++i )
{
if( !isxdigit( head[i] ) )
break;
tbuf[i] = head[i];
}
tbuf[i] = '\0';
if( i > 0 )
c = (char) strtoul( tbuf, NULL, 16 );
else
c = 'x'; // a goofed hex escape sequence, interpret as 'x'
head += i;
break;
default: // 1-3 byte octal escape sequence
--head;
for( i=0; i<3; ++i )
{
if( head[i] < '0' || head[i] > '7' )
break;
tbuf[i] = head[i];
}
tbuf[i] = '\0';
if( i > 0 )
c = (char) strtoul( tbuf, NULL, 8 );
else
c = '\\'; // a goofed octal escape sequence, interpret as '\'
head += i;
break;
}
curText += c;
}
// fall thru
}
else if( *head == '"' ) // end of the non-specctraMode DSN_STRING
{
curTok = DSN_STRING;
++head; // omit this trailing double quote
goto exit;
}
// check for a terminator
if( isStringTerminator( *head ) )
{
curTok = DSN_STRING;
++head;
goto exit;
}
else
curText += *head++;
curText += *head++;
}
} // while
wxString errtxt(_("Un-terminated delimited string") );
THROW_PARSE_ERROR( errtxt, CurSource(), CurLine(), CurLineNumber(), CurOffset() );
#else // old code, did not understand nested quotes
++cur; // skip over the leading delimiter: ",', or $
head = cur;
while( head<limit && !isStringTerminator( *head ) )
++head;
if( head >= limit )
{
// L_unterminated:
wxString errtxt(_("Un-terminated delimited string") );
THROW_PARSE_ERROR( errtxt, CurSource(), CurLine(), CurLineNumber(), CurOffset() );
}
curText.clear();
curText.append( cur, head );
else // specctraMode DSN_STRING
{
++cur; // skip over the leading delimiter: ",', or $
++head; // skip over the trailing delimiter
head = cur;
curTok = DSN_STRING;
goto exit;
#endif
while( head<limit && !isStringTerminator( *head ) )
++head;
if( head >= limit )
{
wxString errtxt(_("Un-terminated delimited string") );
THROW_PARSE_ERROR( errtxt, CurSource(), CurLine(), CurLineNumber(), CurOffset() );
}
curText.clear();
curText.append( cur, head );
++head; // skip over the trailing delimiter
curTok = DSN_STRING;
goto exit;
}
}
// Maybe it is a token we will find in the token table.
@ -1413,7 +1473,6 @@ static const KEYWORD keywords[] = {
class DSNTEST : public wxApp
{
DSNLEXER* lexer;
int nestLevel;

69
common/richio.cpp
View File

@ -282,43 +282,50 @@ int OUTPUTFORMATTER::Print( int nestLevel, const char* fmt, ... ) throw( IO_ERRO
std::string OUTPUTFORMATTER::Quoted( const std::string& aWrapee ) throw( IO_ERROR )
{
// derived class's notion of what a quote character is
char quote = *GetQuoteChar( "(" );
static const char quoteThese[] = "\t ()\n\r";
// Will the string be wrapped based on its interior content?
const char* squote = GetQuoteChar( aWrapee.c_str() );
std::string wrapee = aWrapee; // return this
// Search the interior of the string for 'quote' chars
// and replace them as found with duplicated quotes.
// Note that necessarily any string which has internal quotes will
// also be wrapped in quotes later in this function.
for( unsigned i=0; i<wrapee.size(); ++i )
if( !aWrapee.size() || // quote null string as ""
aWrapee[0]=='#' || // quote a potential s-expression comment, so it is not a comment
aWrapee[0]=='"' || // NextTok() will travel through DSN_STRING path anyway, then must apply escapes
aWrapee.find_first_of( quoteThese ) != std::string::npos )
{
if( wrapee[i] == quote )
std::string ret;
ret.reserve( aWrapee.size()*2 + 2 );
ret += '"';
for( std::string::const_iterator it = aWrapee.begin(); it!=aWrapee.end(); ++it )
{
wrapee.insert( wrapee.begin()+i, quote );
++i;
}
else if( wrapee[i]=='\r' || wrapee[i]=='\n' )
{
// In a desire to maintain accurate line number reporting within DSNLEXER
// a decision was made to make all S-expression strings be on a single
// line. You can embed \n (human readable) in the text but not
// '\n' which is 0x0a.
THROW_IO_ERROR( _( "S-expression string has newline" ) );
switch( *it )
{
case '\n':
ret += '\\';
ret += 'n';
break;
case '\r':
ret += '\\';
ret += 'n';
break;
case '\\':
ret += '\\';
ret += '\\';
break;
case '"':
ret += '\\';
ret += '"';
break;
default:
ret += *it;
}
}
ret += '"';
return ret;
}
if( *squote || strchr( wrapee.c_str(), quote ) )
{
// wrap the beginning and end of the string in a quote.
wrapee.insert( wrapee.begin(), quote );
wrapee.insert( wrapee.end(), quote );
}
return wrapee;
return aWrapee;
}

32
include/dsnlexer.h
View File

@ -89,8 +89,16 @@ protected:
READER_STACK readerStack; ///< all the LINE_READERs by pointer.
LINE_READER* reader; ///< no ownership. ownership is via readerStack, maybe, if iOwnReaders
int stringDelimiter;
bool specctraMode; ///< if true, then:
///< 1) stringDelimiter can be changed
///< 2) Kicad quoting protocol is not in effect
///< 3) space_in_quoted_tokens is functional
///< else not.
char stringDelimiter;
bool space_in_quoted_tokens; ///< blank spaces within quoted strings
bool commentsAreTokens; ///< true if should return comments as tokens
int prevTok; ///< curTok from previous NextTok() call.
@ -205,6 +213,20 @@ public:
virtual ~DSNLEXER();
/**
* Function SetSpecctraMode
* changes the behavior of this lexer into or out of "specctra mode". If
* specctra mode, then:
* 1) stringDelimiter can be changed
* 2) Kicad quoting protocol is not in effect
* 3) space_in_quoted_tokens is functional
* else none of the above are true. The default mode is non-specctra mode, meaning:
* 1) stringDelimiter cannot be changed
* 2) Kicad quoting protocol is in effect
* 3) space_in_quoted_tokens is not functional
*/
void SetSpecctraMode( bool aMode );
/**
* Function PushReader
* manages a stack of LINE_READERs in order to handle nested file inclusion.
@ -298,10 +320,11 @@ public:
* @param aStringDelimiter The character in lowest 8 bits.
* @return int - The old delimiter in the lowest 8 bits.
*/
int SetStringDelimiter( int aStringDelimiter )
char SetStringDelimiter( char aStringDelimiter )
{
int old = stringDelimiter;
stringDelimiter = aStringDelimiter;
if( specctraMode )
stringDelimiter = aStringDelimiter;
return old;
}
@ -314,7 +337,8 @@ public:
bool SetSpaceInQuotedTokens( bool val )
{
bool old = space_in_quoted_tokens;
space_in_quoted_tokens = val;
if( specctraMode )
space_in_quoted_tokens = val;
return old;
}

2
pcbnew/ioascii.cpp
View File

@ -327,7 +327,7 @@ int WinEDA_BasePcbFrame::ReadSetup( LINE_READER* aReader )
}
catch( IO_ERROR& e )
{
#if 0
#if 1
wxString msg;
msg.Printf( wxT( "Error reading PcbPlotParams from %s:\n%s" ),
aReader->GetSource().GetData(),

2
pcbnew/specctra.cpp
View File

@ -2650,7 +2650,7 @@ void SPECCTRA_DB::doFROMTO( FROMTO* growth ) throw( IO_ERROR )
// split apart the <pin_reference>s into 3 separate tokens. Do this by
// turning off the string delimiter in the lexer.
int old = SetStringDelimiter( 0 );
char old = SetStringDelimiter( 0 );
if( !IsSymbol(NextTok() ) )
{

2
pcbnew/specctra.h
View File

@ -3798,6 +3798,8 @@ public:
session = 0;
quote_char += '"';
modulesAreFlipped = false;
SetSpecctraMode( true );
}
virtual ~SPECCTRA_DB()