struct instruction *parse_instruction(void)
{
struct expr *expr;
struct instruction *res;
switch (lookahead[0]->type)
{
case WHILE: return parse_while();
case DO: return parse_do();
case IDENTIFIER: case LPAREN:
expr = parse_expression();
switch(lookahead[0]->type)
{
case ASSIGN: return parse_assignment_instr(expr);
case EOL:
if (expr->exprtype != funcalltype)
{
if (expr->exprtype == binopexprtype
&& expr->val.binopexpr.op == EQ)
{
error(expr->pos, "unexpected =, did you mean <- ?");
exit(1);
}
else
syntaxerror("expected instruction, not expression");
}
eat(EOL);
res = funcallinstr(expr->val.funcall.fun_ident,
expr->val.funcall.args, expr->pos);
free(expr);
return res;
default:
next();
syntaxerror("unexpected %s", tok->val);
return parse_instruction();
}
case RETURN:
eat(RETURN);
if (lookahead[0]->type == EOL)
{
eat(EOL);
return return_stmt(NULL);
}
else
{
expr = parse_expression(); eat(EOL);
return return_stmt(expr);
}
case FOR: return parse_for();
case IF: return parse_if();
case SWITCH: return parse_switch();
case ENDOFFILE: return NULL;
default:
next();
syntaxerror("expected instruction, not %s", tok->val);
return parse_instruction();
}
}
// Parse a statement.
//
// stmt -> block-stmt
// | declaration-stmt
// | expression-stmt
Stmt*
Parser::stmt()
{
switch (lookahead()) {
case semicolon_tok:
return empty_stmt();
case lbrace_tok:
return block_stmt();
case return_kw:
return return_stmt();
case if_kw:
return if_stmt();
case while_kw:
return while_stmt();
case break_kw:
return break_stmt();
case continue_kw:
return continue_stmt();
case var_kw:
case def_kw:
case foreign_kw:
return declaration_stmt();
default:
return expression_stmt();
}
}
static
stmt_code(stream, node, brk, cont, ret) {
/* Handle the null expression. */
if ( !node ) return;
auto op = node[0];
/* For debugging purposes, put a blank line between each statement. */
fputs("\n", stream);
if ( op == 'dcls' ) declaration( stream, node );
else if ( op == 'brea' ) branch( stream, brk );
else if ( op == 'cont' ) branch( stream, cont );
else if ( op == 'retu' ) return_stmt( stream, node, ret );
else if ( op == 'goto' ) goto_stmt( stream, node );
else if ( op == 'if' ) if_stmt( stream, node, brk, cont, ret );
else if ( op == 'whil' ) while_stmt( stream, node, brk, cont, ret );
else if ( op == 'for' ) for_stmt( stream, node, brk, cont, ret );
else if ( op == 'do' ) do_stmt( stream, node, brk, cont, ret );
else if ( op == 'swit' ) switch_stmt( stream, node, brk, cont, ret );
else if ( op == 'case'
|| op == 'defa' ) case_stmt( stream, node, brk, cont, ret );
else if ( op == ':' ) label_stmt( stream, node, brk, cont, ret );
else if ( op == '{}' ) do_block( stream, node, brk, cont, ret );
else expr_code( stream, node, 0 );
}
static void statement()
{
int second_token;
if(token == TOK_IF){
selection_stmt();
}else if(token == TOK_LBRACKET){
compound_stmt();
}else if(token == TOK_ID||token == TOK_AND){
second_token = virtual_get_token(true);
if(second_token == TOK_ASSIGN){
assign_stmt();
}else if(second_token == TOK_LSQUARE){
while(second_token!=TOK_RSQUARE){
second_token = virtual_get_token(false);
if(second_token == TOK_ASSIGN
||second_token == TOK_SEMI
||second_token == TOK_EOF)
{
fprintf( stderr, "line %d: error array var", save_line );
break;
}
}
second_token = virtual_get_token(false);
if(second_token == TOK_ASSIGN){
assign_stmt();
}else{
expression_stmt();
}
}else{
expression_stmt();
}
}else if(token == TOK_WHILE||token == TOK_FOR){
iteration_stmt();
}else if(token == TOK_RETURN){
return_stmt();
}else if(token == TOK_SEMI){
match(TOK_SEMI);
}else
fprintf( stderr, "line %d: error statements", save_line );
}
/* EBNF: statment -> expression-stmt | compound-stmt |
* selection-stmt | iteration-stmt | return-stmt */
static TreeNode * statement (void)
{ TreeNode * t = NULL;
while (token == COMMENT) unexpectedTokenHandling();
switch (token)
{
/* First(expression-stmt)={ID,LPAREN,NUM} */
case ID: case LPAREN: case NUM:
t = expression_stmt(); break;
case CLPAREN: t = compound_stmt(); break;
case IF: t = selection_stmt(); break;
case WHILE: t = iteration_stmt(); break;
case RETURN: t = return_stmt(); break;
default:
unexpectedTokenHandling();
break;
}
return t;
}
void stmt(int level)
{
int this_line = line_cnt;
if(strcmp(tokenPos->textOfLine,"if") == 0)
{
push_child(this_line,IF);
ifstmt(level);
}
else if(strcmp(tokenPos->textOfLine,"while") == 0)
{
push_child(this_line,WHILE);
itestmt(level);
}
else if(strcmp(tokenPos->textOfLine,"return") == 0)
{
push_child(this_line,RETURN);
return_stmt(level);
}
else if(strcmp(tokenPos->textOfLine,"{") == 0)
{
push_child(this_line,COM_STMT);
compound_stmt(level);
}
else if(tokenPos->tokenType == ID || tokenPos->tokenType == NUM || strcmp(tokenPos->textOfLine,"(") == 0 || strcmp(tokenPos->textOfLine,";") == 0)
{
push_child(this_line,EXP_STMT);
exp_stmt(level);
}
else
{
print_err(tokenPos->lineNum,tokenPos->textOfLine,"STMT","IF,WHILE,RETURN,{,ID,NUM,(,;",tokenPos->tokenType);
}
}