Add parsing of if expressions

author: Bad Diode <bd@badd10de.dev> 2021-10-30 08:36:14 +0200
committer: Bad Diode <bd@badd10de.dev> 2021-10-30 08:36:14 +0200
commit: f17b11003fe384b49a7bf844824f23167b6095e0 (patch)
tree: 7129ee8267bf8327d608c1d3a927295929b24631
parent: 4ebcd99d1fadac72ea58ea46012a86c5319ef7e7 (diff)
download: bdl-f17b11003fe384b49a7bf844824f23167b6095e0.tar.gz
bdl-f17b11003fe384b49a7bf844824f23167b6095e0.zip
5 files changed, 95 insertions, 9 deletions
diff --git a/README.md b/README.md
index 321c43d..8ffd273 100755
--- a/README.md
+++ b/README.md
@@ -46,7 +46,7 @@ program       :  <statement>* EOF
 <statement>   :  <definition> | <expression>
 <definition>  :  ( def <symbol> <expression> )
-              |  ( fun ( <symbol>* ) <body> )
+              |  ( fun <symbol> ( <symbol>* ) <body> )
              ;
 <expression>  :  <constant>
diff --git a/src/lexer.c b/src/lexer.c
index f272901..cbcc175 100755
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -12,6 +12,7 @@ static const char* token_str[] = {
    [TOKEN_TRUE]    = "TOKEN_TRUE",
    [TOKEN_FALSE]   = "TOKEN_FALSE",
    [TOKEN_LAMBDA]  = "TOKEN_LAMBDA",
+    [TOKEN_IF]      = "TOKEN_IF",
    [TOKEN_EOF]     = "TOKEN_EOF",
 };
@@ -126,6 +127,7 @@ find_primitive_type(const StringView value) {
    if (TOKEN_IS_KEYWORD(value, "true")) { return TOKEN_TRUE; }
    if (TOKEN_IS_KEYWORD(value, "false")) { return TOKEN_FALSE; }
    if (TOKEN_IS_KEYWORD(value, "lambda")) { return TOKEN_LAMBDA; }
+    if (TOKEN_IS_KEYWORD(value, "if")) { return TOKEN_IF; }
    return TOKEN_SYMBOL;
 }
diff --git a/src/lexer.h b/src/lexer.h
index 4fa4db5..4798a2b 100755
--- a/src/lexer.h
+++ b/src/lexer.h
@@ -20,6 +20,7 @@ typedef enum TokenType {
    // Keywords.
    TOKEN_LAMBDA,
+    TOKEN_IF,
    // End of file.
    TOKEN_EOF,
diff --git a/src/parser.c b/src/parser.c
index 8a6c4ce..5551dd2 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -103,6 +103,7 @@ parse_lambda(Parser *parser, Errors *errors) {
            .line = tok.line,
            .col = tok.col,
        });
+        return NULL;
    }
    // Parse body.
@@ -119,23 +120,81 @@ parse_lambda(Parser *parser, Errors *errors) {
 }
 Object *
-parse_list(Parser *parser, Errors *errors) {
+parse_if(Parser *parser, Errors *errors) {
-    if (errors->n != 0) {
+    Token start = next_token(parser);
+    Object *obj_if = object_alloc(start, OBJ_TYPE_IF);
+    Token tok = peek_token(parser);
+    if (tok.type == TOKEN_RPAREN) {
+        error_push(errors, (Error){
+            .type = ERR_TYPE_PARSER,
+            .value = ERR_NOT_ENOUGH_ARGS,
+            .line = tok.line,
+            .col = tok.col,
+        });
        return NULL;
    }
+    obj_if->condition = parse_tree(parser, errors);
-    Token tok = peek_token(parser);
+    tok = peek_token(parser);
    if (tok.type == TOKEN_RPAREN) {
        error_push(errors, (Error){
            .type = ERR_TYPE_PARSER,
-            .value = ERR_UNBALANCED_PAREN,
+            .value = ERR_NOT_ENOUGH_ARGS,
            .line = tok.line,
            .col = tok.col,
        });
        return NULL;
    }
-    if (tok.type == TOKEN_LAMBDA) {
+    obj_if->expr_true = parse_tree(parser, errors);
-        return parse_lambda(parser, errors);
+    // Optional else expression.
+    tok = peek_token(parser);
+    if (tok.type == TOKEN_RPAREN) {
+        next_token(parser);
+        obj_if->expr_false = NULL;
+        return obj_if;
+    }
+    obj_if->expr_false = parse_tree(parser, errors);
+    tok = peek_token(parser);
+    if (tok.type != TOKEN_RPAREN) {
+        error_push(errors, (Error){
+            .type = ERR_TYPE_PARSER,
+            .value = ERR_TOO_MANY_ARGS,
+            .line = tok.line,
+            .col = tok.col,
+        });
+        return NULL;
+    }
+    next_token(parser);
+    return obj_if;
+}
+Object *
+parse_list(Parser *parser, Errors *errors) {
+    if (errors->n != 0) {
+        return NULL;
+    }
+    Token tok = peek_token(parser);
+    switch (tok.type) {
+        case TOKEN_RPAREN: {
+            error_push(errors, (Error){
+                .type = ERR_TYPE_PARSER,
+                .value = ERR_UNBALANCED_PAREN,
+                .line = tok.line,
+                .col = tok.col,
+            });
+            return NULL;
+        } break;
+        case TOKEN_LAMBDA: {
+            return parse_lambda(parser, errors);
+        } break;
+        case TOKEN_IF: {
+            return parse_if(parser, errors);
+        } break;
+        default: break;
    }
    Token start = previous_token(parser);
@@ -327,13 +386,29 @@ object_display(Object *obj) {
            printf(")");
        } break;
        case OBJ_TYPE_LAMBDA: {
-            printf("#{lambda( ");
+            printf("#{ lambda( ");
            for (size_t i = 0; i < array_size(obj->params); i++) {
                object_display(obj->params[i]);
                printf(" ");
            }
-            printf(")}");
+            printf(") ");
+            for (size_t i = 0; i < array_size(obj->body); i++) {
+                object_display(obj->body[i]);
+                printf(" ");
+            }
+            printf("}");
        } break;
+        case OBJ_TYPE_IF: {
+            printf("#{ if ");
+            object_display(obj->condition);
+            printf(" ");
+            object_display(obj->expr_true);
+            if (obj->expr_false != NULL) {
+                printf(" ");
+                object_display(obj->expr_false);
+            }
+            printf(" }");
+        };
    }
    return;
 }
diff --git a/src/parser.h b/src/parser.h
index 17bd6d6..b2b07c8 100755
--- a/src/parser.h
+++ b/src/parser.h
@@ -12,6 +12,7 @@ typedef enum ObjectType {
    OBJ_TYPE_STRING,
    OBJ_TYPE_PAIR,
    OBJ_TYPE_LAMBDA,
+    OBJ_TYPE_IF,
 } ObjectType;
 typedef struct Object {
@@ -35,6 +36,13 @@ typedef struct Object {
             struct Object **params;
             struct Object **body;
         };
+         // OBJ_TYPE_IF
+         struct {
+             struct Object *condition;
+             struct Object *expr_true;
+             struct Object *expr_false;
+         };
    };
    size_t line;
author	Bad Diode <bd@badd10de.dev>	2021-10-30 08:36:14 +0200
committer	Bad Diode <bd@badd10de.dev>	2021-10-30 08:36:14 +0200
commit	f17b11003fe384b49a7bf844824f23167b6095e0 (patch)
tree	7129ee8267bf8327d608c1d3a927295929b24631
parent	4ebcd99d1fadac72ea58ea46012a86c5319ef7e7 (diff)
download	bdl-f17b11003fe384b49a7bf844824f23167b6095e0.tar.gz bdl-f17b11003fe384b49a7bf844824f23167b6095e0.zip

diff --git a/README.md b/README.md index 321c43d..8ffd273 100755 --- a/README.md +++ b/README.md
@@ -46,7 +46,7 @@ program : <statement>* EOF
46	<statement> : <definition> \| <expression>	46	<statement> : <definition> \| <expression>
47		47
48	<definition> : ( def <symbol> <expression> )	48	<definition> : ( def <symbol> <expression> )
49	\| ( fun ( <symbol>* ) <body> )	49	\| ( fun <symbol> ( <symbol>* ) <body> )
50	;	50	;
51		51
52	<expression> : <constant>	52	<expression> : <constant>


diff --git a/src/lexer.c b/src/lexer.c index f272901..cbcc175 100755 --- a/src/lexer.c +++ b/src/lexer.c
@@ -12,6 +12,7 @@ static const char* token_str[] = {
12	[TOKEN_TRUE] = "TOKEN_TRUE",	12	[TOKEN_TRUE] = "TOKEN_TRUE",
13	[TOKEN_FALSE] = "TOKEN_FALSE",	13	[TOKEN_FALSE] = "TOKEN_FALSE",
14	[TOKEN_LAMBDA] = "TOKEN_LAMBDA",	14	[TOKEN_LAMBDA] = "TOKEN_LAMBDA",
		15	[TOKEN_IF] = "TOKEN_IF",
15	[TOKEN_EOF] = "TOKEN_EOF",	16	[TOKEN_EOF] = "TOKEN_EOF",
16	};	17	};
17		18
@@ -126,6 +127,7 @@ find_primitive_type(const StringView value) {
126	if (TOKEN_IS_KEYWORD(value, "true")) { return TOKEN_TRUE; }	127	if (TOKEN_IS_KEYWORD(value, "true")) { return TOKEN_TRUE; }
127	if (TOKEN_IS_KEYWORD(value, "false")) { return TOKEN_FALSE; }	128	if (TOKEN_IS_KEYWORD(value, "false")) { return TOKEN_FALSE; }
128	if (TOKEN_IS_KEYWORD(value, "lambda")) { return TOKEN_LAMBDA; }	129	if (TOKEN_IS_KEYWORD(value, "lambda")) { return TOKEN_LAMBDA; }
		130	if (TOKEN_IS_KEYWORD(value, "if")) { return TOKEN_IF; }
129		131
130	return TOKEN_SYMBOL;	132	return TOKEN_SYMBOL;
131	}	133	}


diff --git a/src/lexer.h b/src/lexer.h index 4fa4db5..4798a2b 100755 --- a/src/lexer.h +++ b/src/lexer.h
@@ -20,6 +20,7 @@ typedef enum TokenType {
20		20
21	// Keywords.	21	// Keywords.
22	TOKEN_LAMBDA,	22	TOKEN_LAMBDA,
		23	TOKEN_IF,
23		24
24	// End of file.	25	// End of file.
25	TOKEN_EOF,	26	TOKEN_EOF,


diff --git a/src/parser.c b/src/parser.c index 8a6c4ce..5551dd2 100644 --- a/src/parser.c +++ b/src/parser.c
@@ -103,6 +103,7 @@ parse_lambda(Parser parser, Errors errors) {
103	.line = tok.line,	103	.line = tok.line,
104	.col = tok.col,	104	.col = tok.col,
105	});	105	});
		106	return NULL;
106	}	107	}
107		108
108	// Parse body.	109	// Parse body.
@@ -119,23 +120,81 @@ parse_lambda(Parser parser, Errors errors) {
119	}	120	}
120		121
121	Object *	122	Object *
122	parse_list(Parser parser, Errors errors) {	123	parse_if(Parser parser, Errors errors) {
123	if (errors->n != 0) {	124	Token start = next_token(parser);
		125	Object *obj_if = object_alloc(start, OBJ_TYPE_IF);
		126
		127	Token tok = peek_token(parser);
		128	if (tok.type == TOKEN_RPAREN) {
		129	error_push(errors, (Error){
		130	.type = ERR_TYPE_PARSER,
		131	.value = ERR_NOT_ENOUGH_ARGS,
		132	.line = tok.line,
		133	.col = tok.col,
		134	});
124	return NULL;	135	return NULL;
125	}	136	}
		137	obj_if->condition = parse_tree(parser, errors);
126		138
127	Token tok = peek_token(parser);	139	tok = peek_token(parser);
128	if (tok.type == TOKEN_RPAREN) {	140	if (tok.type == TOKEN_RPAREN) {
129	error_push(errors, (Error){	141	error_push(errors, (Error){
130	.type = ERR_TYPE_PARSER,	142	.type = ERR_TYPE_PARSER,
131	.value = ERR_UNBALANCED_PAREN,	143	.value = ERR_NOT_ENOUGH_ARGS,
132	.line = tok.line,	144	.line = tok.line,
133	.col = tok.col,	145	.col = tok.col,
134	});	146	});
135	return NULL;	147	return NULL;
136	}	148	}
137	if (tok.type == TOKEN_LAMBDA) {	149	obj_if->expr_true = parse_tree(parser, errors);
138	return parse_lambda(parser, errors);	150
		151	// Optional else expression.
		152	tok = peek_token(parser);
		153	if (tok.type == TOKEN_RPAREN) {
		154	next_token(parser);
		155	obj_if->expr_false = NULL;
		156	return obj_if;
		157	}
		158	obj_if->expr_false = parse_tree(parser, errors);
		159
		160	tok = peek_token(parser);
		161	if (tok.type != TOKEN_RPAREN) {
		162	error_push(errors, (Error){
		163	.type = ERR_TYPE_PARSER,
		164	.value = ERR_TOO_MANY_ARGS,
		165	.line = tok.line,
		166	.col = tok.col,
		167	});
		168	return NULL;
		169	}
		170	next_token(parser);
		171	return obj_if;
		172	}
		173
		174	Object *
		175	parse_list(Parser parser, Errors errors) {
		176	if (errors->n != 0) {
		177	return NULL;
		178	}
		179
		180	Token tok = peek_token(parser);
		181	switch (tok.type) {
		182	case TOKEN_RPAREN: {
		183	error_push(errors, (Error){
		184	.type = ERR_TYPE_PARSER,
		185	.value = ERR_UNBALANCED_PAREN,
		186	.line = tok.line,
		187	.col = tok.col,
		188	});
		189	return NULL;
		190	} break;
		191	case TOKEN_LAMBDA: {
		192	return parse_lambda(parser, errors);
		193	} break;
		194	case TOKEN_IF: {
		195	return parse_if(parser, errors);
		196	} break;
		197	default: break;
139	}	198	}
140		199
141	Token start = previous_token(parser);	200	Token start = previous_token(parser);
@@ -327,13 +386,29 @@ object_display(Object *obj) {
327	printf(")");	386	printf(")");
328	} break;	387	} break;
329	case OBJ_TYPE_LAMBDA: {	388	case OBJ_TYPE_LAMBDA: {
330	printf("#{lambda( ");	389	printf("#{ lambda( ");
331	for (size_t i = 0; i < array_size(obj->params); i++) {	390	for (size_t i = 0; i < array_size(obj->params); i++) {
332	object_display(obj->params[i]);	391	object_display(obj->params[i]);
333	printf(" ");	392	printf(" ");
334	}	393	}
335	printf(")}");	394	printf(") ");
		395	for (size_t i = 0; i < array_size(obj->body); i++) {
		396	object_display(obj->body[i]);
		397	printf(" ");
		398	}
		399	printf("}");
336	} break;	400	} break;
		401	case OBJ_TYPE_IF: {
		402	printf("#{ if ");
		403	object_display(obj->condition);
		404	printf(" ");
		405	object_display(obj->expr_true);
		406	if (obj->expr_false != NULL) {
		407	printf(" ");
		408	object_display(obj->expr_false);
		409	}
		410	printf(" }");
		411	};
337	}	412	}
338	return;	413	return;
339	}	414	}


diff --git a/src/parser.h b/src/parser.h index 17bd6d6..b2b07c8 100755 --- a/src/parser.h +++ b/src/parser.h
@@ -12,6 +12,7 @@ typedef enum ObjectType {
12	OBJ_TYPE_STRING,	12	OBJ_TYPE_STRING,
13	OBJ_TYPE_PAIR,	13	OBJ_TYPE_PAIR,
14	OBJ_TYPE_LAMBDA,	14	OBJ_TYPE_LAMBDA,
		15	OBJ_TYPE_IF,
15	} ObjectType;	16	} ObjectType;
16		17
17	typedef struct Object {	18	typedef struct Object {
@@ -35,6 +36,13 @@ typedef struct Object {
35	struct Object **params;	36	struct Object **params;
36	struct Object **body;	37	struct Object **body;
37	};	38	};
		39
		40	// OBJ_TYPE_IF
		41	struct {
		42	struct Object *condition;
		43	struct Object *expr_true;
		44	struct Object *expr_false;
		45	};
38	};	46	};
39		47
40	size_t line;	48	size_t line;