add parser

1 files changed, 59 insertions, 0 deletions

diff --git a/src/as_parser.h b/src/as_parser.h
new file mode 100644
index 0000000..268f45a
--- /dev/null
+++ b/src/as_parser.h
@@ -0,0 +1,59 @@
+#include "as_tokenizer.h"
+
+// BNF
+// ===
+//
+// <prog> ::= <stmts>
+// <stmts> ::= <stmt> <newline> | <stmt> <stmts>
+// <stmt> ::= <tag> <instr> | <instr> | <tag>
+// <instr> ::= <op> | <op> <arg> | <op> <label>
+// <tag> ::= <label> :
+// <op> ::= add | sub | mul | div | mod | eq
+
+enum op {
+    ADD, SUB, MUL, DIV, MOD, EQ
+};
+typedef enum op Op;
+
+struct arg {
+    int64_t ival;
+    double fval;
+    const char *sval;
+};
+typedef struct arg Arg;
+
+struct instr {
+    Op op;
+    Arg* arg;
+    const char* labelName;
+};
+typedef struct instr Instr;
+
+struct label {
+    const char* name;
+};
+typedef struct label Label;
+
+struct stmt {
+    Label* tag;
+    Instr* instr;
+};
+typedef struct stmt Stmt;
+
+struct stmts {
+    Stmt** stmts;
+};
+typedef struct stmts Stmts;
+
+struct prog {
+    Stmts *stmts;
+};
+typedef struct prog Prog;
+
+Prog* parseProg(TokenStream *ts);
+Stmt* parseStmt(TokenStream *ts);
+Stmts* parseStmts(TokenStream *ts);
+Instr* parseInstr(TokenStream *ts);
+Label* parseLabel(TokenStream *ts);
+Op parseOp(TokenStream *ts);
+