1 files changed, 77 insertions, 0 deletions
diff --git a/lib/Parser/Parser.cc b/lib/Parser/Parser.cc
new file mode 100644
index 0000000..90dc3a0
--- /dev/null
+++ b/lib/Parser/Parser.cc
@@ -0,0 +1,77 @@
+#include "cps/Parser.h"
+
+using namespace cps;
+
+int Parser::getNextToken() {
+    return CurTok = Lex.gettok();
+}
+
+std::unique_ptr<ExprAST> Parser::ParseNumberExpr() {
+    auto Result = std::make_unique<NumberExprAST>(Lex.NumVal);
+    getNextToken();
+    return Result;
+}
+
+std::unique_ptr<ExprAST> Parser::ParseIdentifierExpr() {
+    std::string IdName = Lex.IdentifierStr;
+    getNextToken();
+    return std::make_unique<VariableExprAST>(IdName);
+}
+
+std::unique_ptr<ExprAST> Parser::ParseExpression() {
+    if (CurTok == tok_number)
+        return ParseNumberExpr();
+    if (CurTok == tok_identifier)
+        return ParseIdentifierExpr();
+    return nullptr;
+}
+
+std::vector<std::unique_ptr<StmtAST>> Parser::Parse() {
+    std::vector<std::unique_ptr<StmtAST>> Statements;
+
+    while (CurTok != tok_eof) {
+        if (CurTok == tok_declare) {
+            // DECLARE <id> : INTEGER
+            getNextToken(); // eat DECLARE
+            if (CurTok != tok_identifier) break; // Error
+            std::string Name = Lex.IdentifierStr;
+            getNextToken(); // eat Name
+            
+            if (CurTok != tok_colon) break; // Error: expected ':'
+            getNextToken(); // eat ':'
+
+            if (CurTok != tok_integer_kw) break; // Error: expected INTEGER
+            getNextToken(); // eat INTEGER
+
+            Statements.push_back(std::make_unique<DeclareStmtAST>(Name));
+        } 
+        else if (CurTok == tok_identifier) {
+            // <id> <- <expr>
+            std::string Name = Lex.IdentifierStr;
+            getNextToken(); // eat Name
+
+            if (CurTok != tok_assign) break; // Error: expected '<-'
+            getNextToken(); // eat '<-'
+
+            auto Expr = ParseExpression();
+            Statements.push_back(std::make_unique<AssignStmtAST>(Name, std::move(Expr)));
+        }
+        else if (CurTok == tok_input) {
+            // INPUT <id>
+            getNextToken(); // eat INPUT
+            if (CurTok != tok_identifier) break;
+            Statements.push_back(std::make_unique<InputStmtAST>(Lex.IdentifierStr));
+            getNextToken();
+        }
+        else if (CurTok == tok_output) {
+            // OUTPUT <expr>
+            getNextToken(); // eat OUTPUT
+            auto Expr = ParseExpression();
+            Statements.push_back(std::make_unique<OutputStmtAST>(std::move(Expr)));
+        }
+        else {
+            getNextToken(); // Skip unknown
+        }
+    }
+    return Statements;
+}