Migrate C preprocessor directive handling (#106)

This commit migrates the handling of C preprocessor directives to the
parser unit. This change unifies the behavior of the lexer unit,
enabling it to focus solely on lexical analysis. Additionally, this
enhances the parsing of preprocessor directives by processing them as
tokens instead of raw strings.

Note: In this commit, several temporary hacks have been introduced to
address issues arising from the previous design's shortcomings (see
lexer.c#lex_accept for details).

src/lexer.c

@@ -58,10 +58,6 @@ typedef enum {
     T_while,
     T_for,
     T_do,
-    T_define,
-    T_undef,
-    T_error,
-    T_include,
     T_typedef,
     T_enum,
     T_struct,
@@ -71,7 +67,16 @@ typedef enum {
     T_case,
     T_break,
     T_default,
-    T_continue
+    T_continue,
+    T_cppd_include,
+    T_cppd_define,
+    T_cppd_undef,
+    T_cppd_error,
+    T_cppd_if,
+    T_cppd_elif,
+    T_cppd_else,
+    T_cppd_endif,
+    T_cppd_ifdef
 } token_t;
 
 char token_str[MAX_TOKEN_LEN];
@@ -189,39 +194,6 @@ char peek_char(int offset)
     return SOURCE[source_idx + offset];
 }
 
-void if_elif_skip_lines()
-{
-    char peek_c;
-    int i;
-
-    do {
-        skip_whitespace();
-        i = 0;
-        do {
-            token_str[i++] = next_char;
-        } while (read_char(0) != '\n');
-        token_str[i] = 0;
-        read_char(1);
-        peek_c = peek_char(1);
-    } while (next_char != '#' || (next_char == '#' && peek_c == 'd'));
-    skip_whitespace();
-}
-
-void ifdef_else_skip_lines()
-{
-    int i;
-
-    do {
-        skip_whitespace();
-        i = 0;
-        do {
-            token_str[i++] = next_char;
-        } while (read_char(0) != '\n');
-        token_str[i] = 0;
-    } while (strcmp(token_str, "#else") && strcmp(token_str, "#endif"));
-    skip_whitespace();
-}
-
 /* check alias defined or not */
 void chk_def(int defined)
 {
@@ -253,108 +225,31 @@ token_t get_next_token()
         skip_whitespace();
 
         if (!strcmp(token_str, "#include")) {
-            do {
-                token_str[i++] = next_char;
-            } while (read_char(0) != '\n');
-            skip_whitespace();
-            return T_include;
+            return T_cppd_include;
         }
         if (!strcmp(token_str, "#define")) {
-            skip_whitespace();
-            return T_define;
+            return T_cppd_define;
         }
         if (!strcmp(token_str, "#undef")) {
-            skip_whitespace();
-            return T_undef;
+            return T_cppd_undef;
         }
         if (!strcmp(token_str, "#error")) {
-            skip_whitespace();
-            return T_error;
+            return T_cppd_error;
         }
         if (!strcmp(token_str, "#if")) {
-            preproc_match = 0;
-            i = 0;
-            do {
-                token_str[i++] = next_char;
-            } while (read_char(0) != '\n');
-            token_str[i] = 0;
-
-            if (!strncmp(token_str, "defined", 7)) {
-                chk_def(1);
-                if (preproc_match) {
-                    skip_whitespace();
-                    return get_next_token();
-                }
-
-                /* skip lines until #elif or #else or #endif */
-                if_elif_skip_lines();
-                return get_next_token();
-            }
+            return T_cppd_if;
         }
         if (!strcmp(token_str, "#elif")) {
-            if (preproc_match) {
-                do {
-                    skip_whitespace();
-                    i = 0;
-                    do {
-                        token_str[i++] = next_char;
-                    } while (read_char(0) != '\n');
-                    token_str[i] = 0;
-                } while (strcmp(token_str, "#endif"));
-                skip_whitespace();
-                return get_next_token();
-            }
-
-            i = 0;
-            do {
-                token_str[i++] = next_char;
-            } while (read_char(0) != '\n');
-            token_str[i] = 0;
-
-            if (!strncmp(token_str, "defined", 7)) {
-                chk_def(1);
-                if (preproc_match) {
-                    skip_whitespace();
-                    return get_next_token();
-                }
-                /* skip lines until #elif or #else or #endif */
-                if_elif_skip_lines();
-                return get_next_token();
-            }
+            return T_cppd_elif;
         }
         if (!strcmp(token_str, "#ifdef")) {
-            preproc_match = 0;
-            i = 0;
-            do {
-                token_str[i++] = next_char;
-            } while (read_char(0) != '\n');
-            token_str[i] = 0;
-            chk_def(0);
-            if (preproc_match) {
-                skip_whitespace();
-                return get_next_token();
-            }
-            /* skip lines until #else or #endif */
-            ifdef_else_skip_lines();
-            return get_next_token();
+            return T_cppd_ifdef;
         }
         if (!strcmp(token_str, "#else")) {
-            /* reach here has 2 possible cases:
-             * 1. reach #ifdef preprocessor directive
-             * 2. conditional expression in #elif is false
-             */
-            if (!preproc_match) {
-                skip_whitespace();
-                return get_next_token();
-            }
-            /* skip lines until #else or #endif */
-            ifdef_else_skip_lines();
-            return get_next_token();
+            return T_cppd_else;
         }
         if (!strcmp(token_str, "#endif")) {
-            preproc_match = 0;
-            skip_whitespace();
-            return get_next_token();
+            return T_cppd_endif;
         }
         error("Unknown directive");
     }
@@ -709,7 +604,12 @@ void skip_macro_body()
 int lex_accept(token_t token)
 {
     if (next_token == token) {
+        /* FIXME: this is a hack, fix aggressive aliasing first */
+        if (token == T_cppd_ifdef)
+            preproc_aliasing = 0;
         next_token = get_next_token();
+        if (token == T_cppd_ifdef)
+            preproc_aliasing = 1;
         return 1;
     }
     return 0;