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-rw-r--r--src/formula.h59
1 files changed, 37 insertions, 22 deletions
diff --git a/src/formula.h b/src/formula.h
index 1eccd36..939eb09 100644
--- a/src/formula.h
+++ b/src/formula.h
@@ -3,15 +3,19 @@
3 3
4#include <stdint.h> 4#include <stdint.h>
5 5
6#include <math.h>
6#include <stack> 7#include <stack>
7#include "sbuffer.h" 8#include "sbuffer.h"
8 9
9#include "exceptionbase.h" 10#include "exceptionbase.h"
11#include "hash.h"
10 12
11subExceptionDecl( ParseException ); 13subExceptionDecl( ParseException );
12 14
13/** 15/**
14 * 16 * Implements a very simple formula parser that allows use of variables and
17 * custom functions. This is based on a simple calculator-type parser that
18 * executes as it processes, accounting for operator precedence and grouping.
15 */ 19 */
16class Formula 20class Formula
17{ 21{
@@ -19,7 +23,29 @@ public:
19 Formula(); 23 Formula();
20 virtual ~Formula(); 24 virtual ~Formula();
21 25
22 double run( const char *sFormula ); 26 double run( char *sFormula );
27
28 typedef Hash<std::string, double> varHash;
29 varHash hVars;
30
31 typedef struct Func
32 {
33 double operator()( double x )
34 {
35 return 0.0;
36 }
37 } Func;
38
39 typedef Hash<std::string, Func> funcHash;
40 funcHash hFunc;
41
42 typedef struct FuncSin : Func
43 {
44 double operator()( double x )
45 {
46 return sin( x );
47 }
48 } FuncSin;
23 49
24private: 50private:
25 enum 51 enum
@@ -32,31 +58,20 @@ private:
32 symOpenParen, 58 symOpenParen,
33 symCloseParen, 59 symCloseParen,
34 symNumber, 60 symNumber,
35 symVariable 61 symVariable,
62 symExponent,
63 symModulus
36 }; 64 };
37 65
38 typedef struct Token 66 typedef uint8_t symType;
39 {
40 Token() {}
41 Token( uint8_t nSym ) : nSym( nSym ) { }
42 Token( uint8_t nSym, double dNum ) : nSym( nSym ) { val.num = dNum; }
43 uint8_t nSym;
44 union
45 {
46 double num;
47 } val;
48 } Token;
49 67
50 std::stack<Token> sToken; 68 std::stack<symType> sOper;
51 Token tLook; 69 std::stack<double> sValue;
52 int nState;
53 SBuffer sBuf;
54 70
55private: 71private:
56 void push(); 72 symType getPrec( symType nOper );
57 void state(); 73 symType nextToken( char **sBuf );
58 Token nextToken(); 74 void reduce( bool bCloseParen = false );
59 void printToken( Token &tok );
60}; 75};
61 76
62#endif 77#endif