refactor(parser): split expression and control flow parsing

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

1 files changed, 146 insertions, 0 deletions

diff --git a/lib/Parser/ParserControlFlow.cc b/lib/Parser/ParserControlFlow.cc
new file mode 100644
index 0000000..cb32466
--- /dev/null
+++ b/lib/Parser/ParserControlFlow.cc
@@ -0,0 +1,146 @@
+#include "cps/Parser.h"
+#include "cps/FunctionAST.h"
+#include <cstdio>
+
+using namespace cps;
+
+std::unique_ptr<StmtAST> Parser::ParseTryStmt() {
+    getNextToken();
+    auto Body = ParseBlock({tok_catch, tok_endtry});
+    if (CurTok != tok_catch) {
+        fprintf(stderr, "error: Expected CATCH in TRY at line %d\n", Lex.getLine());
+        return nullptr;
+    }
+    getNextToken();
+    auto CatchBody = ParseBlock({tok_endtry, tok_catch});
+    if (CurTok != tok_endtry) {
+        fprintf(stderr, "error: Expected ENDTRY after CATCH at line %d\n", Lex.getLine());
+        return nullptr;
+    }
+    getNextToken();
+    return std::make_unique<TryStmtAST>(std::move(Body), std::move(CatchBody));
+}
+
+std::unique_ptr<StmtAST> Parser::ParseIfStmt() {
+    getNextToken();
+    auto Cond = ParseExpression();
+    if (!Cond) return nullptr;
+
+    if (CurTok != tok_then) {
+        fprintf(stderr, "error: expected THEN\n");
+        return nullptr;
+    }
+    getNextToken();
+
+    std::vector<std::unique_ptr<StmtAST>> ThenStmts = ParseBlock({tok_else, tok_endif});
+
+    std::vector<std::unique_ptr<StmtAST>> ElseStmts;
+    if (CurTok == tok_else) {
+        getNextToken();
+        ElseStmts = ParseBlock({tok_endif});
+    }
+
+    if (CurTok != tok_endif) {
+        fprintf(stderr, "error: expected ENDIF\n");
+        return nullptr;
+    }
+    getNextToken();
+
+    return std::make_unique<IfStmtAST>(std::move(Cond), std::move(ThenStmts), std::move(ElseStmts));
+}
+
+std::unique_ptr<StmtAST> Parser::ParseWhileStmt() {
+    getNextToken();
+    auto Cond = ParseExpression();
+    if (!Cond) return nullptr;
+
+    if (CurTok != tok_do) {
+        fprintf(stderr, "error: expected DO after WHILE condition\n");
+        return nullptr;
+    }
+    getNextToken();
+
+    std::vector<std::unique_ptr<StmtAST>> Body = ParseBlock({tok_endwhile});
+
+    if (CurTok != tok_endwhile) {
+        fprintf(stderr, "error: expected ENDWHILE\n");
+        return nullptr;
+    }
+    getNextToken();
+
+    return std::make_unique<WhileStmtAST>(std::move(Cond), std::move(Body));
+}
+
+std::unique_ptr<StmtAST> Parser::ParseRepeatStmt() {
+    getNextToken();
+
+    std::vector<std::unique_ptr<StmtAST>> Body = ParseBlock({tok_until});
+
+    if (CurTok != tok_until) {
+        fprintf(stderr, "error: expected UNTIL\n");
+        return nullptr;
+    }
+    getNextToken();
+
+    auto Cond = ParseExpression();
+    if (!Cond) return nullptr;
+
+    return std::make_unique<RepeatStmtAST>(std::move(Body), std::move(Cond));
+}
+
+std::unique_ptr<StmtAST> Parser::ParseForStmt() {
+    getNextToken();
+    if (CurTok != tok_identifier) {
+        fprintf(stderr, "error: expected identifier after FOR\n");
+        return nullptr;
+    }
+    std::string VarName = Lex.IdentifierStr;
+    getNextToken();
+
+    if (CurTok != tok_assign) {
+        fprintf(stderr, "error: expected '<-' in FOR loop\n");
+        return nullptr;
+    }
+    getNextToken();
+
+    auto Start = ParseExpression();
+    if (!Start) return nullptr;
+
+    if (CurTok != tok_to) {
+        fprintf(stderr, "error: expected TO in FOR loop\n");
+        return nullptr;
+    }
+    getNextToken();
+
+    auto End = ParseExpression();
+    if (!End) return nullptr;
+
+    std::unique_ptr<ExprAST> Step = nullptr;
+    if (CurTok == tok_step) {
+        getNextToken();
+        Step = ParseExpression();
+        if (!Step) return nullptr;
+    }
+
+    std::vector<std::unique_ptr<StmtAST>> Body = ParseBlock({tok_next});
+
+    if (CurTok != tok_next) {
+        fprintf(stderr, "error: expected NEXT\n");
+        return nullptr;
+    }
+    getNextToken();
+    
+    if (CurTok != tok_identifier) {
+        fprintf(stderr, "error: expected identifier after NEXT (e.g., NEXT %s)\n", VarName.c_str());
+        return nullptr;
+    }
+
+    if (Lex.IdentifierStr != VarName) {
+        fprintf(stderr, "error: NEXT identifier '%s' does not match FOR variable '%s'\n",
+                Lex.IdentifierStr.c_str(), VarName.c_str());
+        return nullptr;
+    }
+    getNextToken();
+
+    return std::make_unique<ForStmtAST>(VarName, std::move(Start), std::move(End), std::move(Step), std::move(Body));
+}