Tweaked the stream classes, added an example, and the begining of a formula

parser.

9 files changed, 246 insertions, 0 deletions

diff --git a/src/formula.cpp b/src/formula.cpp
new file mode 100644
index 0000000..7cc1804
--- /dev/null
+++ b/src/formula.cpp
@@ -0,0 +1,157 @@
+#include "formula.h"
+
+subExceptionDef( ParseException );
+
+Formula::Formula()
+{
+}
+
+Formula::~Formula()
+{
+}
+
+double Formula::run( const char *sFormula )
+{
+        sBuf.write( sFormula, strlen( sFormula ) );
+        sBuf.setPos( 0 );
+
+        nState = 0;
+        for(;;)
+        {
+                tLook = nextToken();
+                if( tLook.nSym == symEOS )
+                        break;
+                state();
+        }
+        printf("\n");
+        return 0.0;
+}
+
+void Formula::state()
+{
+        switch( nState )
+        {
+                case 0: // initial expr
+                        switch( tLook.nSym )
+                        {
+                                case symNumber:
+                                        push();
+                                        nState = 1;
+                                        break;
+                        }
+                        break;
+
+                case 1: // binary operator
+                        switch( tLook.nSym )
+                        {
+                                case symAdd:
+                                case symSubtract:
+                                        push();
+                                        nState = 2;
+                                        break;
+
+                                case symMultiply:
+                                case symDivide:
+                                        push();
+                                        nState = 3;
+                                        break;
+                        }
+                        break;
+
+                case 2: // add/subtract
+                        break;
+        }
+}
+
+void Formula::push()
+{
+        printToken( tLook );
+        sToken.push( tLook );
+}
+
+Formula::Token Formula::nextToken()
+{
+        char cbuf;
+        for(;;)
+        {
+                if( sBuf.isEOS() )
+                        return Token( symEOS );
+
+                sBuf.read( &cbuf, 1 );
+                switch( cbuf )
+                {
+                        case '+':
+                                return Token( symAdd );
+
+                        case '-':
+                                return Token( symSubtract );
+
+                        case '*':
+                                return Token( symMultiply );
+
+                        case '/':
+                                return Token( symDivide );
+
+                        case '(':
+                                return Token( symOpenParen );
+
+                        case ')':
+                                return Token( symCloseParen );
+
+                        case ' ':
+                        case '\t':
+                        case '\n':
+                        case '\r':
+                                break;
+
+                        default:
+                                if( cbuf == '.' || (cbuf >= '0' && cbuf <= '9') )
+                                {
+                                        char num[50];
+                                        int nPos = 0;
+                                        bool bDot = false;
+
+                                        for(;;)
+                                        {
+                                                num[nPos++] = cbuf;
+                                                if( cbuf == '.' )
+                                                {
+                                                        if( bDot == false )
+                                                                bDot = true;
+                                                        else
+                                                                throw ParseException(
+                                                                        "Numbers cannot have more than one "
+                                                                        ". in them."
+                                                                        );
+                                                }
+                                                sBuf.read( &cbuf, 1 );
+                                                if( (cbuf != '.' && (cbuf < '0' || cbuf > '9')) || 
+                                                        sBuf.isEOS() )
+                                                {
+                                                        if( !sBuf.isEOS() )     sBuf.seek( -1 );
+                                                        num[nPos] = '\0';
+                                                        return Token( symNumber, strtod( num, NULL ) );
+                                                }
+                                        }
+                                }
+                                break;
+                }
+        }
+}
+
+void Formula::printToken( Token &tok )
+{
+        switch( tok.nSym )
+        {
+                case symEOS:            printf("[EOS] ");                               break;
+                case symAdd:            printf("+ ");                                   break;
+                case symSubtract:       printf("- ");                                   break;
+                case symMultiply:       printf("* ");                                   break;
+                case symDivide:         printf("/ ");                                   break;
+                case symOpenParen:      printf("( ");                                   break;
+                case symCloseParen:     printf(") ");                                   break;
+                case symNumber:         printf("%f ", tok.val.num );    break;
+                default:                        printf("??? ");                                 break;
+        }
+}
+
diff --git a/src/formula.h b/src/formula.h
new file mode 100644
index 0000000..1eccd36
--- /dev/null
+++ b/src/formula.h
@@ -0,0 +1,62 @@
+#ifndef FORMULA_H
+#define FORMULA_H
+
+#include <stdint.h>
+
+#include <stack>
+#include "sbuffer.h"
+
+#include "exceptionbase.h"
+
+subExceptionDecl( ParseException );
+
+/**
+ *
+ */
+class Formula
+{
+public:
+        Formula();
+        virtual ~Formula();
+
+        double run( const char *sFormula );
+
+private:
+        enum
+        {
+                symEOS,
+                symAdd,
+                symSubtract,
+                symMultiply,
+                symDivide,
+                symOpenParen,
+                symCloseParen,
+                symNumber,
+                symVariable
+        };
+
+        typedef struct Token
+        {
+                Token() {}
+                Token( uint8_t nSym ) : nSym( nSym ) { }
+                Token( uint8_t nSym, double dNum ) : nSym( nSym ) { val.num = dNum; }
+                uint8_t nSym;
+                union 
+                {
+                        double num;
+                } val;
+        } Token;
+
+        std::stack<Token> sToken;
+        Token tLook;
+        int nState;
+        SBuffer sBuf;
+
+private:
+        void push();
+        void state();
+        Token nextToken();
+        void printToken( Token &tok );
+};
+
+#endif
diff --git a/src/sbuffer.cpp b/src/sbuffer.cpp
index 0ed0f47..f84f8a3 100644
--- a/src/sbuffer.cpp
+++ b/src/sbuffer.cpp
@@ -60,3 +60,8 @@ void SBuffer::setPosEnd( long pos )
         nPos = fbData.getLength() - pos;
 }
 
+bool SBuffer::isEOS()
+{
+        return nPos == fbData.getLength();
+}
+
diff --git a/src/sbuffer.h b/src/sbuffer.h
index 5352bda..65feb71 100644
--- a/src/sbuffer.h
+++ b/src/sbuffer.h
@@ -24,6 +24,7 @@ public:
         virtual void seek( long offset );
         virtual void setPos( long pos );
         virtual void setPosEnd( long pos );
+        virtual bool isEOS();
 
         FlexBuf &getBuffer()
         {
diff --git a/src/sfile.cpp b/src/sfile.cpp
index 3f5144d..f1de03c 100644
--- a/src/sfile.cpp
+++ b/src/sfile.cpp
@@ -67,3 +67,8 @@ void SFile::setPosEnd( long pos )
         fseek( fh, pos, SEEK_END );
 }
 
+bool SFile::isEOS()
+{
+        return feof( fh );
+}
+
diff --git a/src/sfile.h b/src/sfile.h
index f276ad2..b51e5bc 100644
--- a/src/sfile.h
+++ b/src/sfile.h
@@ -19,6 +19,7 @@ public:
         virtual void seek( long offset );
         virtual void setPos( long pos );
         virtual void setPosEnd( long pos );
+        virtual bool isEOS();
 
 private:
         FILE *fh;
diff --git a/src/stream.cpp b/src/stream.cpp
index 99c25f2..856a58d 100644
--- a/src/stream.cpp
+++ b/src/stream.cpp
@@ -7,3 +7,4 @@ Stream::Stream()
 Stream::~Stream()
 {
 }
+
diff --git a/src/stream.h b/src/stream.h
index 32e5432..e086e28 100644
--- a/src/stream.h
+++ b/src/stream.h
@@ -18,6 +18,7 @@ public:
         virtual void seek( long offset ) = 0;
         virtual void setPos( long pos ) = 0;
         virtual void setPosEnd( long pos ) = 0;
+        virtual bool isEOS() = 0;
 
 private:
 
diff --git a/src/tests/formula.cpp b/src/tests/formula.cpp
new file mode 100644
index 0000000..599a264
--- /dev/null
+++ b/src/tests/formula.cpp
@@ -0,0 +1,13 @@
+#include "formula.h"
+
+int main( int argc, char *argv[] )
+{
+        if( argc < 2 ) return 0;
+
+        Formula f;
+        double dOut = f.run( argv[1] );
+        printf("Final:  %f\n", dOut );
+        
+        return 0;
+}
+