From dbf52344ae5e370f5e2e140ed57e37008aea2248 Mon Sep 17 00:00:00 2001
From: Konstantin Nazarov <mail@knazarov.com>
Date: Sun, 18 Aug 2024 20:01:40 +0100
Subject: [PATCH] Implement reading of code from files in the entry point

---
 CMakeLists.txt |  2 ++
 README.md      |  2 +-
 example.vli    |  3 +++
 src/common.hpp |  5 +++--
 src/error.hpp  |  1 +
 src/fio.cpp    | 39 +++++++++++++++++++++++++++++++++++++++
 src/fio.hpp    |  7 +++++++
 src/vli.cpp    | 29 ++++++++++++++++++++++-------
 8 files changed, 78 insertions(+), 10 deletions(-)
 create mode 100644 example.vli
 create mode 100644 src/fio.cpp
 create mode 100644 src/fio.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 852dea1..609e7be 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,6 +20,7 @@ target_sources(vm_lib
   src/utf8.cpp
   src/compiler.cpp
   src/opcode.cpp
+  src/fio.cpp
 
   PUBLIC
   FILE_SET HEADERS
@@ -37,6 +38,7 @@ target_sources(vm_lib
   src/utf8.hpp
   src/compiler.hpp
   src/opcode.hpp
+  src/fio.hpp
 )
 
 add_executable(vli src/vli.cpp)
diff --git a/README.md b/README.md
index f3a78f5..4032411 100644
--- a/README.md
+++ b/README.md
@@ -69,7 +69,7 @@ To run:
 ```sh
 cmake .
 make
-./vli
+./vli example.vli
 ```
 
 To run tests:
diff --git a/example.vli b/example.vli
new file mode 100644
index 0000000..84dc672
--- /dev/null
+++ b/example.vli
@@ -0,0 +1,3 @@
+;; Check that lambdas can be passed as arguments
+
+((lambda (f y) (f y)) (lambda (x) (* x x)) 2)
diff --git a/src/common.hpp b/src/common.hpp
index 22b3ed3..a591b62 100644
--- a/src/common.hpp
+++ b/src/common.hpp
@@ -459,8 +459,7 @@ class String : public Object {
     return _value->data[idx];
   }
 
-  Result<String> concat(const char* rhs) {
-    uint64_t rhs_size = strlen(rhs);
+  Result<String> concat(const char* rhs, uint64_t rhs_size) {
     uint64_t lhs_size = size();
     uint64_t res_size = lhs_size + rhs_size;
 
@@ -473,6 +472,8 @@ class String : public Object {
     return String(TRY(MkGcRoot(pod)));
   }
 
+  Result<String> concat(const char* rhs) { return concat(rhs, strlen(rhs)); }
+
   Result<String> concat(const char32_t* rhs, uint64_t rhs_size) {
     uint64_t lhs_size = size();
     uint64_t res_size = lhs_size + rhs_size;
diff --git a/src/error.hpp b/src/error.hpp
index f88fa4e..dced58c 100644
--- a/src/error.hpp
+++ b/src/error.hpp
@@ -15,6 +15,7 @@ enum class ErrorCode {
   EndOfProgram,
   CompilationError,
   ArgumentCountMismatch,
+  IOError,
 };
 
 void seterr(const char* err);
diff --git a/src/fio.cpp b/src/fio.cpp
new file mode 100644
index 0000000..a343eea
--- /dev/null
+++ b/src/fio.cpp
@@ -0,0 +1,39 @@
+#include "fio.hpp"
+
+#include <cstdlib>
+
+Result<String> read_fh(FILE* file) {
+  size_t chunk_size = 1024;
+  const size_t buf_size = chunk_size;
+  size_t pos = 0;
+
+  char buf[chunk_size];
+
+  String res = TRY(String::create(""));
+
+  while (1) {
+    size_t num_bytes = fread(&buf[pos], 1, chunk_size, file);
+
+    if (ferror(stdin)) {
+      return ERROR(IOError);
+    }
+    res = TRY(res.concat(buf, num_bytes));
+    if (num_bytes < chunk_size) break;
+  }
+
+  return std::move(res);
+}
+
+Result<String> read_file(const char* filename) {
+  FILE* fh = fopen(filename, "r");
+
+  if (!fh) {
+    return ERROR(IOError);
+  }
+
+  auto res = read_fh(fh);
+  fclose(fh);
+  return res;
+}
+
+Result<String> read_stdin() { return read_fh(stdin); }
diff --git a/src/fio.hpp b/src/fio.hpp
new file mode 100644
index 0000000..9129193
--- /dev/null
+++ b/src/fio.hpp
@@ -0,0 +1,7 @@
+#pragma once
+
+#include "common.hpp"
+
+Result<String> read_file(const char* filename);
+
+Result<String> read_stdin();
diff --git a/src/vli.cpp b/src/vli.cpp
index cf0014e..3aaee7e 100644
--- a/src/vli.cpp
+++ b/src/vli.cpp
@@ -1,20 +1,35 @@
+#include <unistd.h>
+
+#include <cstdio>
 #include <iostream>
 
 #include "arena.hpp"
 #include "common.hpp"
 #include "compiler.hpp"
+#include "die.hpp"
+#include "fio.hpp"
 #include "reader.hpp"
 #include "vm.hpp"
 #include "writer.hpp"
 
 StaticArena<64 * 1024 * 1024> arena;
 
-Result<void> run() {
-  // auto code_str = TRY(String::create("(* (+ 1 2 3) (/ 4 2))"));
-  auto code_str =
-      TRY(String::create("((lambda (f y) (f y)) (lambda (x) (* x x)) 2)"));
+Result<void> run(int argc, const char* argv[]) {
+  String src = DIEX(String::create(""));
+  if (argc == 1) {
+    if (isatty(STDIN_FILENO)) {
+      die("Code expected at stdin, not a tty.\n");
+    }
+    src = TRY(read_stdin());
+  } else {
+    src = TRY(read_file(argv[1]));
+  }
 
-  auto parsed = TRY(read_one(code_str));
+  // auto code_str = TRY(String::create("(* (+ 1 2 3) (/ 4 2))"));
+  // auto code_str =
+  // TRY(String::create("((lambda (f y) (f y)) (lambda (x) (* x x)) 2)"));
+
+  auto parsed = TRY(read_one(src));
   auto code_str_written = TRY(write_one(parsed));
 
   TRY(arena_gc());
@@ -36,7 +51,7 @@ Result<void> run() {
   return Result<void>();
 }
 
-int main() {
-  DIEX(run());
+int main(int argc, const char* argv[]) {
+  DIEX(run(argc, argv));
   return 0;
 }