From 8f98dc579af1993ec85bd849656c4835b4039dd6 Mon Sep 17 00:00:00 2001
From: Stefan Weigl-Bosker <stefan@s00.xyz>
Date: Mon, 23 Feb 2026 22:18:22 -0500
Subject: [willow]: frontend plumbing (#13)

...
---
 willow/tools/willowc/lib/sourcemanager.cpp | 75 ++++++++++++++++++++++++++++--
 1 file changed, 71 insertions(+), 4 deletions(-)

(limited to 'willow/tools/willowc/lib/sourcemanager.cpp')

diff --git a/willow/tools/willowc/lib/sourcemanager.cpp b/willow/tools/willowc/lib/sourcemanager.cpp
index e2a8e72..a30c76e 100644
--- a/willow/tools/willowc/lib/sourcemanager.cpp
+++ b/willow/tools/willowc/lib/sourcemanager.cpp
@@ -1,6 +1,9 @@
+#include <cassert>
 #include <filesystem>
-
 #include <fstream>
+#include <iostream>
+#include <string_view>
+
 #include <sourcemanager.hpp>
 
 namespace willowc {
@@ -11,9 +14,14 @@ std::optional<FileID> SourceManager::addFile(std::string_view _path) {
   std::filesystem::path uncanonical_path{_path};
   auto path = std::filesystem::weakly_canonical(uncanonical_path, ec);
   if (ec) {
-    return false;
+    return std::nullopt;
   }
-  std::string display_path = path.make_preferred();
+
+  std::filesystem::path display_path = path;
+  display_path.make_preferred();
+  std::string display = display_path.string();
+
+  assert(!getFileID(display));
 
   if (!std::filesystem::exists(path, ec) || ec)
     return std::nullopt;
@@ -33,9 +41,68 @@ std::optional<FileID> SourceManager::addFile(std::string_view _path) {
   f.read(buf.get(), filesize);
 
   const FileID id = file_table.size();
-  file_table.push_back(File{std::move(display_path), std::move(buf)});
+  file_table.emplace_back(std::move(display), std::string(_path), std::move(buf), filesize);
+  ids[file_table.back().path] = id;
 
   return id;
 }
 
+std::optional<FileID> SourceManager::getFileID(const std::string &path) {
+  auto it = ids.find(path);
+
+  if (it != ids.end())
+    return it->second;
+
+  return std::nullopt;
+}
+
+std::optional<FileID> SourceManager::addStdIn() {
+  std::string content{std::istreambuf_iterator<char>(std::cin),
+                      std::istreambuf_iterator<char>()};
+
+  if (std::cin.bad())
+    return std::nullopt;
+
+  std::size_t size = content.size();
+  auto buf = std::make_unique<char[]>(size);
+  const FileID id = file_table.size();
+  file_table.emplace_back("<stdin>", "<stdin>", std::move(buf), size);
+  ids[file_table.back().path] = id;
+  return id;
+}
+
+willow::Location SourceManager::File::getLoc(std::size_t offset) {
+  size_t line_start = offset;
+  while (line_start != 0) {
+    if (this->buf[--line_start] != '\n')
+      continue;
+
+    line_start++;
+    break;
+  }
+
+  uint32_t col = offset - line_start + 1;
+  auto it = linecache_.find(line_start);
+
+  if (it != linecache_.end())
+    return willow::Location{display_path, it->second, col, offset};
+
+  auto back = linecache_.rbegin();
+  auto i = back->first;
+  auto line = back->second;
+  assert(i < line_start);
+  for (; i < line_start; i++) {
+    if (buf[i] == '\n') {
+      line = line + 1;
+      size_t next_start = i + 1;
+
+      if (next_start <= size)
+        linecache_.insert({next_start, ++line});
+    }
+  }
+  linecache_.insert({line_start, line});
+  return willow::Location{
+      display_path, line, static_cast<uint32_t>(offset - line_start + 1), offset};
+}
+
 } // namespace willowc
-- 
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