add yacc programs

3 files changed, 47 insertions, 0 deletions

diff --git a/9/input b/9/input
new file mode 100644
index 0000000..01efb5e
--- /dev/null
+++ b/9/input
@@ -0,0 +1 @@
+aaabbbbc
diff --git a/9/main.l b/9/main.l
new file mode 100644
index 0000000..04c6bf0
--- /dev/null
+++ b/9/main.l
@@ -0,0 +1,16 @@
+%{
+#include "y.tab.h"
+extern int yylval;
+%}
+
+%%
+a return A;
+b return B;
+c return C;
+. return yytext[0];
+\n return 0;
+%%
+
+int yywrap() {
+    return 1;
+}
diff --git a/9/main.y b/9/main.y
new file mode 100644
index 0000000..0db29c1
--- /dev/null
+++ b/9/main.y
@@ -0,0 +1,30 @@
+%{
+#include <stdio.h>
+#include <stdlib.h>
+int yylex();
+int yyerror(char *);
+%}
+
+%token A B C
+
+%%
+S: X Y
+ |
+ ;
+X: A X B
+ |
+ ;
+Y: B Y C
+ |
+ ;
+%%
+
+int main() {
+    yyparse();
+    printf("valid string");
+}
+
+int yyerror(char *s) {
+    printf("error: %s", s);
+    exit(0);
+}