diff options
| -rw-r--r-- | include/ast.h | 4 | ||||
| -rw-r--r-- | src/ast.c | 9 | ||||
| -rw-r--r-- | src/interpreter.c | 13 | ||||
| -rw-r--r-- | src/lexer.l | 2 | ||||
| -rw-r--r-- | src/parser.y | 4 |
5 files changed, 28 insertions, 4 deletions
diff --git a/include/ast.h b/include/ast.h index c619c72..8482aab 100644 --- a/include/ast.h +++ b/include/ast.h @@ -4,7 +4,7 @@ typedef enum { NT_SKIP, NT_ASSIGN, NT_SEQ, NT_IF, NT_WHILE, - NT_INT, NT_VAR, NT_AOP, NT_BOP, NT_NOT, NT_ROP + NT_INT, NT_VAR, NT_AOP, NT_BOP, NT_NOT, NT_ROP, NT_LET } NodeType; typedef enum { AOP_ADD, AOP_SUB, AOP_MUL } AOp; @@ -24,6 +24,7 @@ typedef struct ASTNode { struct { BOp bop; struct ASTNode *bexp1, *bexp2; } d_bop; struct { struct ASTNode *bexp; } d_not; struct { ROp rop; struct ASTNode *aexp1, *aexp2; } d_rop; + struct { struct ASTNode *var, *aexp, *stm; } d_let; } u; } ASTNode; @@ -39,6 +40,7 @@ ASTNode *ast_aop(AOp aop, ASTNode *aexp1, ASTNode *aexp2); ASTNode *ast_bop(BOp bop, ASTNode *bexp1, ASTNode *bexp2); ASTNode *ast_not(ASTNode *bexp); ASTNode *ast_rop(ROp rop, ASTNode *aexp1, ASTNode *aexp2); +ASTNode *ast_let(ASTNode *var, ASTNode *aexp, ASTNode *stm); void ast_free(ASTNode *node); @@ -88,6 +88,15 @@ ASTNode *ast_rop(ROp rop, ASTNode *aexp1, ASTNode *aexp2) { return node; } +ASTNode *ast_let(ASTNode *var, ASTNode *aexp, ASTNode *stm) { + ASTNode *node = new_node(NT_LET); + node->u.d_let.var = var; + node->u.d_let.aexp = aexp; + node->u.d_let.stm = stm; + return node; +} + + void ast_free(ASTNode *node) { if (!node) return; switch (node->type) { diff --git a/src/interpreter.c b/src/interpreter.c index 93b1bdb..4449847 100644 --- a/src/interpreter.c +++ b/src/interpreter.c @@ -76,9 +76,9 @@ void exec_stmt(hashmap_t context, ASTNode *node) { case NT_SKIP: return; case NT_ASSIGN: { - char *var = node->u.d_assign.var->u.d_var.name; + char *name = node->u.d_assign.var->u.d_var.name; int val = eval_aexpr(context, node->u.d_assign.aexp); - context_set(context, var, val); + context_set(context, name, val); return; } case NT_SEQ: @@ -96,6 +96,15 @@ void exec_stmt(hashmap_t context, ASTNode *node) { exec_stmt(context, node->u.d_while.stm); } return; + case NT_LET: { + char *name = node->u.d_let.var->u.d_var.name; + int old_val = context_get(context, name); + int new_val = eval_aexpr(context, node->u.d_let.aexp); + context_set(context, name, new_val); + exec_stmt(context, node->u.d_let.stm); + context_set(context, name, old_val); + return; + } default: fprintf(stderr, "Bad stmt node %d\n", node->type); exit(EXIT_FAILURE); diff --git a/src/lexer.l b/src/lexer.l index c9aaff0..26ac229 100644 --- a/src/lexer.l +++ b/src/lexer.l @@ -17,6 +17,8 @@ WHITESPACE [ \t\r\n]+ "end" { return TOKEN_END; } "while" { return TOKEN_WHILE; } "do" { return TOKEN_DO; } +"var" { return TOKEN_VAR; } +"in" { return TOKEN_IN; } "(" { return TOKEN_LEFT_PARENTHESIS; } ")" { return TOKEN_RIGHT_PARENTHESIS; } diff --git a/src/parser.y b/src/parser.y index 9a94480..cb3544e 100644 --- a/src/parser.y +++ b/src/parser.y @@ -29,7 +29,7 @@ void yyerror(const char *s) { %token TOKEN_LEFT_PARENTHESIS TOKEN_RIGHT_PARENTHESIS %token TOKEN_SEMICOLON %token TOKEN_SKIP -%token TOKEN_IF TOKEN_THEN TOKEN_ELSE TOKEN_END TOKEN_WHILE TOKEN_DO +%token TOKEN_IF TOKEN_THEN TOKEN_ELSE TOKEN_END TOKEN_WHILE TOKEN_DO TOKEN_VAR TOKEN_IN %token TOKEN_PLUS TOKEN_MINUS TOKEN_MULTIPLY %token TOKEN_NOT TOKEN_OR TOKEN_AND %token TOKEN_EQUALS TOKEN_NOT_EQUALS TOKEN_LESS_THAN TOKEN_LESS_EQUAL TOKEN_GREATER_THAN TOKEN_GREATER_EQUAL @@ -54,6 +54,8 @@ statement : TOKEN_SKIP { $$ = ast_if($2, $4, $6); } | TOKEN_WHILE boolean_expression TOKEN_DO statement TOKEN_END { $$ = ast_while($2, $4); } + | TOKEN_VAR variable TOKEN_ASSIGN arithmetic_expression TOKEN_IN statement TOKEN_END + { $$ = ast_let($2, $4, $6); } ; variable : TOKEN_IDENTIFIER |