/*
* Tiny BASIC
* Statement Handling Header
*
* Released as Public Domain by Damian Gareth Walker 2019
* Created: 15-Aug-2019
*/
#ifndef __STATEMENT_H__
#define __STATEMENT_H__
/* Pre-requisite headers */
#include "expression.h"
/* Forward Declarations */
typedef struct program_line_node ProgramLineNode;
typedef struct statement_node StatementNode;
typedef struct output_node OutputNode;
typedef struct variable_list_node VariableListNode;
/*
* Data Definitions
*/
/* The types of output allowed in a PRINT statement */
typedef enum {
OUTPUT_STRING, /* a literal string */
OUTPUT_EXPRESSION /* an expression */
} OutputClass;
/* The relational operators */
typedef enum {
RELOP_EQUAL, /* = */
RELOP_UNEQUAL, /* <> or >< */
RELOP_LESSTHAN, /* < */
RELOP_LESSOREQUAL, /* <= */
RELOP_GREATERTHAN, /* > */
RELOP_GREATEROREQUAL /* >= */
} RelationalOperator;
/* Expressions or strings to output */
typedef struct output_node {
OutputClass class; /* string or expression */
union {
char *string; /* a literal string to output */
ExpressionNode *expression; /* an expression to output */
} output;
OutputNode *next; /* the next output node, if any */
} OutputNode;
/* List of variables to input */
typedef struct variable_list_node {
int variable; /* the variable */
VariableListNode *next; /* next variable, if any */
} VariableListNode;
/*
* Structures for statements in general
*/
/* Let Statement Node */
typedef struct {
int variable; /* the variable to assign, 1..26 for A..Z */
ExpressionNode *expression; /* the expression to assign to it */
} LetStatementNode;
/* If Statement Node */
typedef struct {
ExpressionNode *left; /* the left-hand expression */
RelationalOperator op; /* the comparison operator used */
ExpressionNode *right; /* the right-hand expression */
StatementNode *statement; /* statement to execute if condition is true */
} IfStatementNode;
/* Print Statement Node */
typedef struct {
OutputNode *first; /* the first expression to print */
} PrintStatementNode;
/* Input Statement Node */
typedef struct {
VariableListNode *first; /* the first variable to input */
} InputStatementNode;
/* Goto Statement Node */
typedef struct {
ExpressionNode *label; /* an expression that computes the label */
} GotoStatementNode;
/* Gosub Statement Node */
typedef struct {
ExpressionNode *label; /* an expression that computes the label */
} GosubStatementNode;
/* Statement classes */
typedef enum {
STATEMENT_NONE, /* unknown statement */
STATEMENT_LET, /* LET variable=expression */
STATEMENT_IF, /* IF condition THEN statement */
STATEMENT_GOTO, /* GOTO expression */
STATEMENT_GOSUB, /* GOSUB expression */
STATEMENT_RETURN, /* RETURN */
STATEMENT_END, /* END */
STATEMENT_PRINT, /* PRINT print-list */
STATEMENT_INPUT /* INPUT var-list */
} StatementClass;
/* Common Statement Node */
typedef struct statement_node {
StatementClass class; /* which type of statement this is */
union {
LetStatementNode *letn; /* a LET statement */
IfStatementNode *ifn; /* an IF statement */
GotoStatementNode *goton; /* a GOTO statement */
GosubStatementNode *gosubn; /* a GOSUB statement */
/* a RETURN statement requires no extra data */
/* an END statement requires no extra data */
PrintStatementNode *printn; /* a PRINT statement */
InputStatementNode *inputn; /* an INPUT statement */
} statement;
} StatementNode;
/* a program line */
typedef struct program_line_node {
int label; /* line label */
StatementNode *statement; /* the current statement */
ProgramLineNode *next; /* the next statement */
} ProgramLineNode;
/* the program */
typedef struct {
ProgramLineNode *first; /* first program statement */
} ProgramNode;
/*
* Function Declarations
*/
/*
* LET statement constructor
* returns:
* LetStatementNode* the created LET statement
*/
LetStatementNode *statement_create_let (void);
/*
* IF statement constructor
* returns:
* IfStatementNode* the created IF statement
*/
IfStatementNode *statement_create_if (void);
/*
* GOTO Statement Constructor
* returns:
* GotoStatementNode* the new GOTO statement
*/
GotoStatementNode *statement_create_goto (void);
/*
* GOSUB Statement Constructor
* returns:
* GosubStatementNode* the new GOSUB statement
*/
GosubStatementNode *statement_create_gosub (void);
/*
* PRINT statement constructor
* returns:
* PrintStatementNode* the created PRINT statement
*/
PrintStatementNode *statement_create_print (void);
/*
* INPUT statement constructor
* returns:
* InputStatementNode* initialised INPUT statement data
*/
InputStatementNode *statement_create_input (void);
/*
* Statement constructor
* returns:
* StatementNode* the newly-created blank statement
*/
StatementNode *statement_create (void);
/*
* Statement destructor
* params:
* StatementNode* statement the doomed statement
*/
void statement_destroy (StatementNode *statement);
/*
* Program Line Constructor
* returns:
* ProgramLineNode* the new program line
*/
ProgramLineNode *program_line_create (void);
/*
* Program Line Destructor
* params:
* ProgramLineNode* program_line the doomed program line
* params:
* ProgramLineNode* the next program line
*/
ProgramLineNode *program_line_destroy (ProgramLineNode *program_line);
/*
* Program Constructor
* returns:
* ProgramNode* the constructed program
*/
ProgramNode *program_create (void);
/*
* Program Destructor
* params:
* ProgramNode* program the doomed program
*/
void program_destroy (ProgramNode *program);
#endif