Extract parser and add x64 assembly emission

build.sh

@@ -1,4 +1,20 @@
-set -euo pipefail
+# set -euo pipefail
+
+assert_eq() {
+   expected="$1"
+   actual="$2"
+   if [ "$expected" != "$actual" ]; then
+       echo "assert failed: expected '$expected', got '$actual'"
+       exit 1
+   fi
+}
+
+verify_expr() {
+    ./main "$1"
+    clang out.s -o test
+    ./test
+    assert_eq $? $2
+}
 
 if [[ ! -e build ]]; then
     mkdir build
@@ -7,4 +23,10 @@ cd build
 clang -o meta $(realpath ../meta.c) -g -Wall -Wextra -Wshadow -fdiagnostics-absolute-paths
 ./meta > ../meta_gen.c
 clang -o main $(realpath ../main.c) -g -Wall -Wextra -Wshadow -fdiagnostics-absolute-paths
-./main
+
+./main
+verify_expr "2+1-1" 2
+verify_expr "(2+1-1)*3" 6
+
+
+echo done