132 lines
2.7 KiB
C++
132 lines
2.7 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 used by the lexer.
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// TODO: move to more appropriate place.
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char* substr(const char* source, int from, int to);
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enum ExprType {
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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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};
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typedef struct Expr Expr;
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// Represents SQL expressions (i.e. literals, operators, column_refs).
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// TODO: When destructing a placeholder expression, we might need to alter the placeholder_list.
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struct Expr {
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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 described by a single character e.g:
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// + - * / < > = %
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// Non-trivial are: <> <= >= LIKE ISNULL NOT
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enum OperatorType {
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SIMPLE_OP,
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// Binary operators.
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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 operators.
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NOT,
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UMINUS,
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ISNULL
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};
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Expr(ExprType type);
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// Interesting side-effect:
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// Making the destructor virtual used to cause segmentation faults.
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// TODO: inspect.
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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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int64_t ival2;
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OperatorType op_type;
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char op_char;
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bool distinct;
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// Convenience accessor methods.
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bool isType(ExprType e_type);
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bool isLiteral();
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bool hasAlias();
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bool hasTable();
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char* getName();
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bool isSimpleOp();
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bool isSimpleOp(char op);
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// Static constructors.
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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, bool distinct);
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static Expr* makePlaceholder(int id);
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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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