126 lines
2.5 KiB
C++
126 lines
2.5 KiB
C++
#ifndef __EXPRESSION_H__
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#define __EXPRESSION_H__
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#include <stdlib.h>
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#include <memory>
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namespace hsql {
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// Helper function
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char* substr(const char* source, int from, int to);
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typedef enum {
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kExprLiteralFloat,
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kExprLiteralString,
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kExprLiteralInt,
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kExprStar,
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kExprPlaceholder,
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kExprColumnRef,
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kExprFunctionRef,
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kExprOperator
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} ExprType;
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typedef struct Expr Expr;
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struct Expr {
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/**
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* Operator types. These are important for expressions of type kExprOperator
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* Trivial types are those that can be descriped by a sigle character e.g:
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* + - * / < > = %
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* Non-trivial are:
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* <> <= >= LIKE ISNULL NOT
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*/
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typedef enum {
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SIMPLE_OP,
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// Binary
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NOT_EQUALS,
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LESS_EQ,
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GREATER_EQ,
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LIKE,
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NOT_LIKE,
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AND,
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OR,
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// Unary
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NOT,
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UMINUS,
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ISNULL
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} OperatorType;
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Expr(ExprType type) :
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type(type),
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expr(NULL),
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expr2(NULL),
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name(NULL),
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table(NULL),
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alias(NULL) {};
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// Interesting side-effect:
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// Making the destructor virtual causes segmentation faults
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~Expr();
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ExprType type;
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Expr* expr;
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Expr* expr2;
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char* name;
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char* table;
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char* alias;
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float fval;
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int64_t ival;
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OperatorType op_type;
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char op_char;
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/**
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* Convenience accessor methods
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*/
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inline bool isType(ExprType e_type) { return e_type == type; }
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inline bool hasAlias() { return alias != NULL; }
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inline bool hasTable() { return table != NULL; }
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inline char* getName() {
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if (alias != NULL) return alias;
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else return name;
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}
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inline bool isSimpleOp() { return op_type == SIMPLE_OP; }
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inline bool isSimpleOp(char op) { return isSimpleOp() && op_char == op; }
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/**
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* Static expression constructors
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*/
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static Expr* makeOpUnary(OperatorType op, Expr* expr);
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static Expr* makeOpBinary(Expr* expr1, char op, Expr* expr2);
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static Expr* makeOpBinary(Expr* expr1, OperatorType op, Expr* expr2);
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static Expr* makeLiteral(int64_t val);
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static Expr* makeLiteral(double val);
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static Expr* makeLiteral(char* val);
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static Expr* makeColumnRef(char* name);
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static Expr* makeColumnRef(char* table, char* name);
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static Expr* makeFunctionRef(char* func_name, Expr* expr);
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};
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// Zero initializes an Expr object and assigns it to a space in the heap
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// For Hyrise we still had to put in the explicit NULL constructor
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// http://www.ex-parrot.com/~chris/random/initialise.html
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// Unused
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#define ALLOC_EXPR(var, type) \
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Expr* var; \
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do { \
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Expr zero = {type}; \
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var = (Expr*)malloc(sizeof *var); \
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*var = zero; \
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} while(0);
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#undef ALLOC_EXPR
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} // namespace hsql
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#endif
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