add yacc programs

3 files changed, 56 insertions, 0 deletions

diff --git a/10/input b/10/input
new file mode 100644
index 0000000..fdfb61b
--- /dev/null
+++ b/10/input
@@ -0,0 +1 @@
+1+2-3*6/2
diff --git a/10/main.l b/10/main.l
new file mode 100644
index 0000000..9962054
--- /dev/null
+++ b/10/main.l
@@ -0,0 +1,22 @@
+%{
+extern int yylval;
+%}
+
+d [0-9]+
+
+%%
+"+" return ADD;
+"-" return SUB;
+"*" return MUL;
+"/" return DIV;
+[0-9]+ {
+    yylval = atoi(yytext);
+    return NUM;
+};
+. return yytext[0];
+\n return 0;
+%%
+
+int yywrap() {
+    return 1;
+}
diff --git a/10/main.y b/10/main.y
new file mode 100644
index 0000000..f45e23f
--- /dev/null
+++ b/10/main.y
@@ -0,0 +1,33 @@
+%{
+#include <stdio.h>
+#include <stdlib.h>
+int yylex();
+int yyerror(char *);
+%}
+
+%token ADD SUB MUL DIV NUM
+%left ADD SUB MUL DIV
+
+%%
+R: E {
+    printf("result: %d", $$);
+    return 0;
+ }
+E: E ADD T { $$ = $1 + $3; }
+ | E SUB T { $$ = $1 - $3; }
+ | T
+ ;
+T: T MUL NUM { $$ = $1 * $3; }
+ | T DIV NUM { $$ = $1 / $3; }
+ | NUM { $$ = $1; }
+ ;
+%%
+
+int main() {
+    yyparse();
+}
+
+int yyerror(char *s) {
+    printf("error: %s", s);
+    exit(0);
+}