error codes

CMakeLists.txt

@@ -15,6 +15,7 @@ add_executable(Graph
     "parser.c"
     "tree.c"
     "ps_graph.c"
+    "error_buffer.c"
 )
 
 # Optionally, you can set compiler warnings

error_buffer.c

@@ -0,0 +1,47 @@
+#include "error_buffer.h"
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+void error_buffer_init(struct error_buffer *eb) {
+    eb->err = ERR_NO_ERR;
+    eb->text_len = 0;
+    eb->text[0] = 0;
+    /* memset(eb->text, 0xAA, MAX_ERROR_MESSAGE_LENGTH); */
+}
+
+void error_set(struct error_buffer *eb, enum error_code err) {
+    eb->err = err;
+}
+
+enum error_code error_get(const struct error_buffer *eb) {
+    return eb->err;
+}
+
+void error_printf(struct error_buffer *eb, const char *format, ...) {
+    va_list args;
+    int space = MAX_ERROR_MESSAGE_LENGTH - eb->text_len;
+    int write_size;
+
+    if (space == 0)
+        return;
+
+    va_start(args, format);
+    write_size = vsnprintf(eb->text + eb->text_len, MAX_ERROR_MESSAGE_LENGTH - eb->text_len, format, args);
+    va_end(args);
+
+    if (write_size < 0)
+        return;
+
+    if (write_size < space) {
+        eb->text_len += write_size;
+    } else {
+        eb->text_len = MAX_ERROR_MESSAGE_LENGTH;
+    }
+
+    /* eb->text[eb->text_len] = 0; */
+}
+
+const char *error_get_text(const struct error_buffer *eb) {
+    return eb->text;
+}

error_buffer.h

@@ -0,0 +1,31 @@
+#ifndef ERROR_CODE_H
+#define ERROR_CODE_H
+
+#include <stdlib.h>
+
+#define MAX_ERROR_MESSAGE_LENGTH 512
+
+enum error_code {
+    ERR_NO_ERR              = 0,
+    ERR_INVALID_ARGS        = 1,
+    ERR_INVALID_FUNCTION    = 2,
+    ERR_INVALID_FILENAME    = 3,
+    ERR_INVALID_LIMITS      = 4,    
+    ERR_BAD_ALLOC           = 5
+};
+
+struct error_buffer {
+    enum error_code err;
+    char text[MAX_ERROR_MESSAGE_LENGTH];
+    size_t text_len;
+};
+
+void error_buffer_init(struct error_buffer *eb);
+
+void error_set(struct error_buffer *eb, enum error_code err);
+void error_printf(struct error_buffer *eb, const char *format, ...);
+
+enum error_code error_get(const struct error_buffer *eb);
+const char *error_get_text(const struct error_buffer *eb);
+
+#endif /* ERROR_CODE_H */

lex.c

@@ -1,32 +1,16 @@
-#include <stdlib.h>
-#include <stdio.h>
-
 #include "lex.h"
 
-struct lexer {
+#include <stdlib.h>
-    const char* start;
+#include <stdio.h>
-    const char* prev_p;
+#include <string.h>
-    const char* p;
-    struct token tok;
-};
 
-struct lexer *lex_create(const char *str) {
+void lex_init(struct lexer *lex, const char *str) {
-    struct lexer *lex = malloc(sizeof(struct lexer));
+    error_buffer_init(&lex->eb);
-
-    if (!lex)
-        return NULL;
 
     lex->start = str;
     lex->prev_p = str;
     lex->p = str;
-    
     lex_next(lex);
-
-    return lex;
-}
-
-void lex_free(struct lexer *lex) {
-    free(lex);
 }
 
 static int is_whitespace(char p) {
@@ -119,8 +103,9 @@ void lex_next(struct lexer *lex) {
 
     if (try_number(lex)) return;
 
-    fprintf(stderr, "Lexer error - unrecognized sequence \"%s\"\n", lex->p);
+    error_set(&lex->eb, ERR_INVALID_FUNCTION);
-    lex_print_position(lex);
+    error_printf(&lex->eb, "Unrecognized sequence \"%s\"\n", lex->p);
+    lex_print_position(lex, &lex->eb);
 
     lex->tok.type = TOK_ERROR;
     return;
@@ -130,19 +115,34 @@ struct token *lex_token(struct lexer *lex) {
     return &lex->tok;
 }
 
-void lex_print_position(const struct lexer *lex) {
+void lex_print_position(const struct lexer *lex, struct error_buffer *eb) {
-    int i;
+    size_t pos = lex->prev_p - lex->start;
-    int pos = lex->prev_p - lex->start;
+    size_t i;
-    
+    size_t input_len = strlen(lex->start);
-    fprintf(stderr, "At character %d\n", pos);
-    fprintf(stderr, "   %s\n", lex->start);
-    fprintf(stderr, "   ");
-    for (i = 0; i < pos; ++i)
-        fprintf(stderr, " ");
 
-    fprintf(stderr, "^\n----------------------------------------------------\n");
+    error_printf(eb, "At character %d\n", pos);
+    error_printf(eb, "   %s\n", lex->start);
+    error_printf(eb, "   ");
+
+    for (i = 0; i < input_len; ++i) {
+        char c = '_';
+        if (i == pos)
+            c = '^';
+
+        error_printf(eb, "%c", c);
+    }
+
+    error_printf(eb, "\n");
+    /* error_printf(eb,  "\n----------------------------------------------------\n"); */
 }
 
+enum error_code lex_get_error(const struct lexer *lex) {
+    return error_get(&lex->eb);
+}
+
+const char *lex_get_error_text(const struct lexer *lex) {
+    return error_get_text(&lex->eb);
+}
 
 #ifdef LEX_DEBUG
 

lex.h

@@ -1,6 +1,8 @@
 #ifndef LEX_H
 #define LEX_H
 
+#include "error_buffer.h"
+
 #define LEX_DEBUG
 
 enum token_type {
@@ -43,19 +45,26 @@ struct token {
     } val;
 };
 
-struct lexer;
+struct lexer {
+    const char *start;
+    const char *prev_p;
+    const char *p;
+    struct token tok;
+    struct error_buffer eb;
+};
 
-extern struct lexer *lex_create(const char *str);
+void lex_init(struct lexer *lex, const char *str);
-extern void lex_free(struct lexer *lex);
 
-extern void lex_next(struct lexer *lex);
+void lex_next(struct lexer *lex);
-extern struct token *lex_token(struct lexer *lex);
+struct token *lex_token(struct lexer *lex);
 
-extern void lex_print_position(const struct lexer *lex);
+void lex_print_position(const struct lexer *lex, struct error_buffer *eb);
 
+enum error_code lex_get_error(const struct lexer *lex);
+const char *lex_get_error_text(const struct lexer *lex);
 
 #ifdef LEX_DEBUG
-extern void lex_debug_print_token(const struct token *tok);
+void lex_debug_print_token(const struct token *tok);
 #endif /* LEX_DEBUG */
 
 #endif /* LEX_H */

main.c

@@ -6,40 +6,40 @@
 
 int main(int argc, char *argv[]) { 
 
-    struct lexer *lex;
+    struct parser parser;
     struct expr_node *node;
+    FILE *file;
+    struct graph_range graph;
 
     if (argc < 2) {
         printf("Usage: %s <expression>\n", argv[0]);
         return 1;
     }
 
-    lex = lex_create(argv[1]);
+    parser_init(&parser);
+    node = parser_parse(&parser, argv[1]);
 
-    node = parse_expression(lex);
+    if (!node) {
-    lex_free(lex);
+        fprintf(stderr, "%s", parser_get_error_text(&parser));
-
+        return parser_get_error(&parser);
-    if (node) {
-        FILE *file;
-        struct graph_range graph;
-
-        graph.xmin = -20.0;
-        graph.xmax = 20.0;
-        graph.ymin = -20.0;
-        graph.ymax = 20.0;
-        graph.step = 0.01;
-
-        file = fopen("out.ps", "w");
-        ps_export_graph(file, node, &graph);
-        fclose(file);
-
-        file = fopen("graph.dot", "w");
-        node_debug_print_gv(node, file);
-        fclose(file);
-
-        node_free(node);
     }
 
+    graph.xmin = -20.0;
+    graph.xmax = 20.0;
+    graph.ymin = -20.0;
+    graph.ymax = 20.0;
+    graph.step = 0.01;
+
+    file = fopen("out.ps", "w");
+    ps_export_graph(file, node, &graph);
+    fclose(file);
+
+    file = fopen("graph.dot", "w");
+    node_debug_print_gv(node, file);
+    fclose(file);
+
+    node_free(node);
+
 
     return 0;
 }

parser.c

@@ -2,81 +2,101 @@
 #include <stdio.h>
 #include "parser.h"
 
-static int token_is(struct lexer *lex, enum token_type type) {
+static struct token *get_token(struct parser *parser) {
-    return lex_token(lex)->type == type;
+    return lex_token(&parser->lexer);
 }
 
-static int accept(struct lexer *lex, enum token_type type) {
+static int token_is(struct parser *parser, enum token_type type) {
-    if (token_is(lex, type)) {
+    return get_token(parser)->type == type;
-        lex_next(lex);
+}
+
+static double token_num(struct parser *parser) {
+    return get_token(parser)->val.num;
+}
+
+static enum math_fn token_fn(struct parser *parser) {
+    return get_token(parser)->val.fn;
+}
+
+static void next_token(struct parser *parser) {
+    lex_next(&parser->lexer);
+}
+
+static int accept_token(struct parser *parser, enum token_type type) {
+    if (token_is(parser, type)) {
+        next_token(parser);
         return 1;
     }
     return 0;
 }
 
-static double token_num(struct lexer *lex) {
+static void error_bad_alloc(struct parser *parser) {
-    return lex_token(lex)->val.num;
+    error_set(&parser->eb, ERR_BAD_ALLOC);
+    error_printf(&parser->eb, "Out of memory\n");
 }
 
-static enum math_fn token_fn(struct lexer *lex) {
+static void error_expected_one_of(struct parser *parser, const int expected[]) {
-    return lex_token(lex)->val.fn;
-}
-
-static void error_expected_one_of(struct lexer *lex, const int expected[], enum token_type got) {
     static const char* token_name[] = {
         "end of expression",
         "lexer error",
         "constant",
         "+",
-            "-",
+        "-",
-            "*",
+        "*",
-            "/",
+        "/",
-            "^",
+        "^",
-            "x",
+        "x",
-            "function name",
+        "function name",
-            "(",
+        "(",
-            ")"
+        ")"
     };
 
-    int separate = 0;
+    size_t i;
 
-    fprintf(stderr, "Syntax error - expected ");
+    enum token_type got = get_token(parser)->type;
 
-    for (; *expected >= 0; ++expected) {
+    if (got == TOK_ERROR) {
-        if (separate)
+        error_set(&parser->eb, lex_get_error(&parser->lexer));
-            fprintf(stderr, ", ");
+        error_printf(&parser->eb, "Lexer error - %s", lex_get_error_text(&parser->lexer));
-        else
+        return;
-            separate = 1;
-
-        fprintf(stderr, "'%s'", token_name[*expected]);
     }
 
-    fprintf(stderr, " - but got '%s'\n", token_name[got]);
+    error_set(&parser->eb, ERR_INVALID_FUNCTION);
+    error_printf(&parser->eb, "Syntax error - expected ");
 
-    lex_print_position(lex);
+    for (i = 0; expected[i] >= 0; ++i) {
+        if (i > 0)
+            error_printf(&parser->eb, ", ");
+
+        error_printf(&parser->eb, "'%s'", token_name[expected[i]]);
+    }
+
+    error_printf(&parser->eb, " - but got '%s'\n", token_name[got]);
+
+    lex_print_position(&parser->lexer, &parser->eb);
 }
 
-static void error_expected_single(struct lexer* lex, enum token_type expected, enum token_type got) {
+static void error_expected_single(struct parser *parser, enum token_type expected) {
     static int expected_arr[] = { -1, -1 };
     expected_arr[0] = expected;
-    error_expected_one_of(lex, expected_arr, got);
+    error_expected_one_of(parser, expected_arr);
 }
 
-struct expr_node* parse_subexpression(struct lexer* lex);
+static struct expr_node* parse_subexpression(struct parser *parser);
 
-static struct expr_node* parse_bracketed(struct lexer* lex) {
+static struct expr_node* parse_bracketed(struct parser *parser) {
     struct expr_node* node;
 
-    if (!accept(lex, TOK_LEFT_PAREN)) {
+    if (!accept_token(parser, TOK_LEFT_PAREN)) {
-        error_expected_single(lex, TOK_LEFT_PAREN, lex_token(lex)->type);
+        error_expected_single(parser, TOK_LEFT_PAREN);
         return NULL;
     }
 
-    if (!(node = parse_subexpression(lex)))
+    if (!(node = parse_subexpression(parser)))
         return NULL;
 
-    if (!accept(lex, TOK_RIGHT_PAREN)) {
+    if (!accept_token(parser, TOK_RIGHT_PAREN)) {
-        error_expected_single(lex, TOK_RIGHT_PAREN, lex_token(lex)->type);
+        error_expected_single(parser, TOK_RIGHT_PAREN);
         node_free(node);
         return NULL;
     }
@@ -84,60 +104,72 @@ static struct expr_node* parse_bracketed(struct lexer* lex) {
     return node;
 }
 
-static struct expr_node *parse_base(struct lexer *lex) {
+static struct expr_node *parse_base(struct parser *parser) {
     struct expr_node *node, *inner;
 
-    if (token_is(lex, TOK_NUMBER)) {
+    if (token_is(parser, TOK_NUMBER)) {
-        double val = token_num(lex);
+        double val = token_num(parser);
-        lex_next(lex);
+        next_token(parser);
-        return node_create_const(val);
+        if (!(node = node_create_const(val))) {
-    }
+            error_bad_alloc(parser);
-
-    if (accept(lex, TOK_X)) {
-        return node_create_x();
-    }
-
-    if (token_is(lex, TOK_FUNCTION)) {
-        enum math_fn fn = token_fn(lex);
-        lex_next(lex);
-
-        if (!(inner = parse_bracketed(lex)))
             return NULL;
-
-        if (!(node = node_create_fn(fn, inner))) {
-            node_free(inner);
         }
 
         return node;
     }
 
-    if (token_is(lex, TOK_LEFT_PAREN)) {
+    if (accept_token(parser, TOK_X)) {
-        return parse_bracketed(lex);
+        if (!(node = node_create_x())) {
+            error_bad_alloc(parser);
+            return NULL;
+        }
+        return node;
+    }
+
+    if (token_is(parser, TOK_FUNCTION)) {
+        enum math_fn fn = token_fn(parser);
+        next_token(parser);
+
+        if (!(inner = parse_bracketed(parser)))
+            return NULL;
+
+        if (!(node = node_create_fn(fn, inner))) {
+            node_free(inner);
+            error_bad_alloc(parser);
+            return NULL;
+        }
+
+        return node;
+    }
+
+    if (token_is(parser, TOK_LEFT_PAREN)) {
+        return parse_bracketed(parser);
     }
 
     {
         static const int expected[] = { TOK_NUMBER, TOK_X, TOK_FUNCTION, TOK_LEFT_PAREN, -1 };
-        error_expected_one_of(lex, expected, lex_token(lex)->type);
+        error_expected_one_of(parser, expected);
     }
 
     return NULL;
 }
 
-static struct expr_node* parse_unary(struct lexer* lex);
+static struct expr_node *parse_unary(struct parser *parser);
 
-static struct expr_node* parse_factor(struct lexer* lex) {
+static struct expr_node *parse_factor(struct parser *parser) {
     struct expr_node* node, * new_node, * inner;
 
-    if (!(node = parse_base(lex)))
+    if (!(node = parse_base(parser)))
         return NULL;
 
-    if (accept(lex, TOK_POWER)) {
+    if (accept_token(parser, TOK_POWER)) {
-        if (!(inner = parse_unary(lex))) {
+        if (!(inner = parse_unary(parser))) {
             node_free(node);
             return NULL;
         }
 
         if (!(new_node = node_create_pow(node, inner))) {
+            error_bad_alloc(parser);
             node_free(node);
             node_free(inner);
             return NULL;
@@ -149,14 +181,15 @@ static struct expr_node* parse_factor(struct lexer* lex) {
     return node;
 }
 
-static struct expr_node* parse_unary(struct lexer *lex) {
+static struct expr_node* parse_unary(struct parser *parser) {
-    if (accept(lex, TOK_MINUS)) {
+    if (accept_token(parser, TOK_MINUS)) {
         struct expr_node *node, *inner;
         
-        if (!(inner = parse_factor(lex)))
+        if (!(inner = parse_factor(parser)))
             return NULL;
 
         if (!(node = node_create_neg(inner))) {
+            error_bad_alloc(parser);
             node_free(inner);
             return NULL;
         }
@@ -164,32 +197,33 @@ static struct expr_node* parse_unary(struct lexer *lex) {
         return node;
     }
 
-    accept(lex, TOK_PLUS);
+    accept_token(parser, TOK_PLUS);
-    return parse_factor(lex);
+    return parse_factor(parser);
 }
 
-static struct expr_node *parse_term(struct lexer *lex) {
+static struct expr_node *parse_term(struct parser *parser) {
     struct expr_node *node, *new_node, *inner;
 
-    if (!(node = parse_unary(lex)))
+    if (!(node = parse_unary(parser)))
         return NULL;
 
     while (1) {
         struct expr_node *(*create_node)(struct expr_node *left, struct expr_node *right);
 
-        if (accept(lex, TOK_MULTIPLY))
+        if (accept_token(parser, TOK_MULTIPLY))
             create_node = node_create_mult;
-        else if (accept(lex, TOK_DIVIDE))
+        else if (accept_token(parser, TOK_DIVIDE))
             create_node = node_create_div;
         else
             break;
 
-        if (!(inner = parse_unary(lex))) {
+        if (!(inner = parse_unary(parser))) {
             node_free(node);
             return NULL;
         }
 
         if (!(new_node = create_node(node, inner))) {
+            error_bad_alloc(parser);
             node_free(node);
             node_free(inner);
             return NULL;
@@ -201,47 +235,29 @@ static struct expr_node *parse_term(struct lexer *lex) {
     return node;
 }
 
-struct expr_node *parse_subexpression(struct lexer *lex) {
+static struct expr_node *parse_subexpression(struct parser *parser) {
     struct expr_node *node, *new_node, *inner;
-    
-    /*
-    if (accept(lex, TOK_MINUS)) {
-        if (!(term = parse_term(lex)))
-            return NULL;
 
-        if (!(node = node_create_neg(term))) {
+    if (!(node = parse_term(parser)))
-            node_free(term);
-            return NULL;
-        }
-    }
-    else {
-        accept(lex, TOK_PLUS);
-
-        if (!(node = parse_term(lex)))
-            return NULL;
-    }
-    
-    */
-
-    if (!(node = parse_term(lex)))
         return NULL;
 
     while (1) {
         struct expr_node *(*create_node)(struct expr_node *left, struct expr_node *right);
 
-        if (accept(lex, TOK_PLUS))
+        if (accept_token(parser, TOK_PLUS))
             create_node = node_create_add;
-        else if (accept(lex, TOK_MINUS))
+        else if (accept_token(parser, TOK_MINUS))
             create_node = node_create_sub;
         else
             break;
 
-        if (!(inner = parse_term(lex))) {
+        if (!(inner = parse_term(parser))) {
             node_free(node);
             return NULL;
         }
 
         if (!(new_node = create_node(node, inner))) {
+            error_bad_alloc(parser);
             node_free(node);
             node_free(inner);
             return NULL;
@@ -253,17 +269,35 @@ struct expr_node *parse_subexpression(struct lexer *lex) {
     return node;
 }
 
-struct expr_node *parse_expression(struct lexer *lex) {
+static struct expr_node *parse_expression(struct parser *parser) {
     struct expr_node *node;
 
-    if (!(node = parse_subexpression(lex)))
+    if (!(node = parse_subexpression(parser)))
         return NULL;
 
-    if (!token_is(lex, TOK_EOF)) {
+    if (!token_is(parser, TOK_EOF)) {
-        error_expected_single(lex, TOK_EOF, lex_token(lex)->type);
+        error_expected_single(parser, TOK_EOF);
         node_free(node);
         return NULL;
     }
 
     return node;
+}
+
+void parser_init(struct parser *parser) {
+    error_buffer_init(&parser->eb);
+}
+
+struct expr_node *parser_parse(struct parser *parser, const char *str) {
+    lex_init(&parser->lexer, str);
+    return parse_expression(parser);
+
+}
+
+enum error_code parser_get_error(const struct parser *parser) {
+    return error_get(&parser->eb);
+}
+
+const char *parser_get_error_text(const struct parser *parser) {
+    return error_get_text(&parser->eb);
 }

parser.h

@@ -2,7 +2,17 @@
 #define PARSER_H
 
 #include "tree.h"
+#include "lex.h"
 
-extern struct expr_node *parse_expression(struct lexer *lex);
+struct parser {
+    struct lexer lexer;
+    struct error_buffer eb;
+};
+
+void parser_init(struct parser *parser);
+struct expr_node *parser_parse(struct parser *parser, const char *str);
+
+enum error_code parser_get_error(const struct parser *parser);
+const char *parser_get_error_text(const struct parser *parser);
 
 #endif /* PARSER_H */