feat: implement CIE 9.1 text file handling (OPENFILE/READFILE/WRITEFILE/CLOSEFILE/EOF)

Front end: OPENFILE/READFILE/WRITEFILE/CLOSEFILE plus reserved mode
keywords READ/WRITE/APPEND (RANDOM reserved with a dedicated
not-implemented error); statement nodes in new FileAST.h, parsing in new
ParserFile.cc; EOF joins the Builtins table as the 12th builtin and
CallExprAST now carries a line number for its runtime diagnostics.

Runtime: new FileHandler (StringHandler-shaped leaf) lazily synthesizes
internal __cps_file_* helper functions and a 16-slot open-file table
keyed by filename content (strcmp — STRING '=' is pointer identity).
EOF is an fgetc/ungetc peek; READFILE grows a malloc/realloc line buffer
and strips a trailing CR; fopen uses text modes so mingw-w64 line
translation works. File-free programs get byte-identical IR. All misuse
(not open, wrong mode, reopen, fopen failure, read past EOF, table full)
dies with the existing "[Fatal] line N:" pattern via a new
RuntimeCheck::emitErrorAndExit overload taking runtime printf args.

Also fixes a pre-existing ArithmeticHandler hole surfaced by adversarial
review: mixed-width integer operands (i1 BOOLEAN / i8 CHAR vs i64) now
widen via ZExt instead of emitting invalid IR, and remaining type
mismatches get a clean diagnostic; -EOF(f) and -IS_NUM(x) compile.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

1 files changed, 75 insertions, 0 deletions

diff --git a/include/cps/FileHandler.h b/include/cps/FileHandler.h
new file mode 100644
index 0000000..aaad6a0
--- /dev/null
+++ b/include/cps/FileHandler.h
@@ -0,0 +1,75 @@
+#pragma once
+#include "cps/FileMode.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+
+namespace cps {
+
+class RuntimeCheck;
+
+// Emits the text-file runtime: a fixed-size open-file table plus internal
+// __cps_file_* helper functions, synthesized once on first use so programs
+// without file statements keep their IR unchanged. The table is keyed by
+// filename *content* (strcmp) — pseudocode STRING equality is pointer
+// identity, so the same file may be named by many different buffers.
+// Leaf module: methods only take and return llvm::Value*s; expression
+// evaluation, type coercion and the symbol table stay in CodeGen.
+class FileHandler {
+    llvm::LLVMContext &Context;
+    llvm::IRBuilder<> &Builder;
+    llvm::Module &Module;
+    RuntimeCheck &Checker;
+
+    static constexpr uint64_t TableSize = 16;
+    bool RuntimeEmitted = false;
+
+    // libc — declared lazily on first file use
+    llvm::FunctionCallee FopenFunc, FcloseFunc, FgetcFunc, UngetcFunc,
+                         FputsFunc, FputcFunc, MallocFunc, ReallocFunc,
+                         StrcmpFunc;
+
+    // open-file table
+    llvm::GlobalVariable *FileNames = nullptr;   // [TableSize x ptr] STRING passed to OPENFILE
+    llvm::GlobalVariable *FileHandles = nullptr; // [TableSize x ptr] FILE*
+    llvm::GlobalVariable *FileModes = nullptr;   // [TableSize x i8]  0 = free slot, else FileMode
+
+    llvm::Value *ModeReadStr = nullptr, *ModeWriteStr = nullptr, *ModeAppendStr = nullptr;
+    llvm::Value *ErrOpenFail = nullptr, *ErrAlreadyOpen = nullptr, *ErrTableFull = nullptr,
+                *ErrNotOpen = nullptr, *ErrNotRead = nullptr, *ErrNotWrite = nullptr,
+                *ErrPastEof = nullptr;
+
+    // synthesized helpers (internal linkage; pseudocode identifiers cannot
+    // start with '_', so these names are un-collidable)
+    llvm::Function *FindFn = nullptr, *OpenFn = nullptr, *ReadFn = nullptr,
+                   *WriteFn = nullptr, *CloseFn = nullptr, *EofFn = nullptr;
+
+    void setupExternalFunctions();
+    void setupGlobals();
+    void ensureRuntime();
+
+    llvm::Function *createHelper(const char *Name, llvm::FunctionType *FT);
+    llvm::Value *emitSlotGEP(llvm::GlobalVariable *Table, llvm::Type *ElemTy, llvm::Value *Idx);
+    llvm::Value *emitLookupOrFail(llvm::Value *Name, llvm::Value *Line);
+    void buildFindFn();
+    void buildOpenFn();
+    void buildReadFn();
+    void buildWriteFn();
+    void buildCloseFn();
+    void buildEofFn();
+
+public:
+    FileHandler(llvm::LLVMContext &Ctx, llvm::IRBuilder<> &B, llvm::Module &M,
+                RuntimeCheck &RC);
+
+    // NameStr/DataStr are already-coerced STRING ptrs; Line is the statement's
+    // source line for runtime diagnostics. All methods null-check and bail;
+    // the caller (CodeGen) does the diagnostics.
+    void emitOpen(llvm::Value *NameStr, FileMode Mode, int Line);
+    llvm::Value *emitRead(llvm::Value *NameStr, int Line); // returns STRING ptr
+    void emitWrite(llvm::Value *NameStr, llvm::Value *DataStr, int Line);
+    void emitClose(llvm::Value *NameStr, int Line);
+    llvm::Value *emitEof(llvm::Value *NameStr, int Line); // returns i1
+};
+
+} // namespace cps