From 26ab539d3c43c6f92051debd168443694ebcd50c Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sat, 20 Dec 2025 12:52:23 +0300
Subject: [PATCH] Preprocess tabs when printing error context

---
 apps/interpreter/source/main.cpp | 21 +++++++++++++++++++--
 plans.txt                        |  2 +-
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/apps/interpreter/source/main.cpp b/apps/interpreter/source/main.cpp
index 961dfc3..b57f41a 100644
--- a/apps/interpreter/source/main.cpp
+++ b/apps/interpreter/source/main.cpp
@@ -25,16 +25,33 @@ std::string extract_nth_line(std::filesystem::path const & path, std::size_t n)
 	return {};
 }
 
+std::size_t replace_tabs_with_spaces(std::string & str, std::size_t count)
+{
+	std::string replaced;
+	for (char c : str)
+	{
+		if (c == '\t')
+			replaced.append(count, ' ');
+		else
+			replaced.append(1, c);
+	}
+	std::swap(str, replaced);
+	return str.size() - replaced.size();
+}
+
 void print_error_context(std::filesystem::path const & file, pslang::ast::location const & location)
 {
 	if (location.begin.line == location.end.line)
 	{
 		std::size_t max_line_number_digits = std::floor(std::log10(location.begin.line)) + 1;
 
+		auto line = extract_nth_line(file, location.begin.line);
+		auto extra = replace_tabs_with_spaces(line, 2);
+
 		std::cerr << std::endl;
 		std::cerr << "line " << std::setw(max_line_number_digits) << std::right << location.begin.line << ": ";
-		std::cerr << extract_nth_line(file, location.begin.line) << std::endl;
-		std::cerr << std::string(std::max<std::size_t>(location.begin.column, 1) - 1 + max_line_number_digits + 7, ' ') << std::string(location.end.column - location.begin.column, '^') << std::endl;
+		std::cerr << line << std::endl;
+		std::cerr << std::string(std::max<std::size_t>(location.begin.column, 1) - 1 + max_line_number_digits + 7 + extra, ' ') << std::string(location.end.column - location.begin.column, '^') << std::endl;
 	}
 }
 
diff --git a/plans.txt b/plans.txt
index b61a6d8..1e78ada 100644
--- a/plans.txt
+++ b/plans.txt
@@ -4,6 +4,7 @@ Future plans:
 * Introduce type checking & inference as a separate pre-execution/compilation AST pass + add type information into expression nodes
 * Pointers: pointer types, address-of operator (&), dereferencing, scope-based lifetime tracking in interpreter
 * Function overloading: separate functions from values (again) in interpreter, allow casting to specific function type to take function value
+* C FFI: `foreign func sin(x : f32) -> f32`
 * Const propagation: annotate expression AST nodes that are computable in compile-time
 * Generic parameters: can be either values or `t : type`, but always compile-time
 * Generic structs: `struct <t : type, n : u64> array:`, require explicitly specifying parameters when instantiated (used as a type or creating a value)
@@ -14,7 +15,6 @@ Future plans:
 
 Backlog:
 * Mutually recursive functions
-* Figure out indentation: keep tabs - what to do with printing errors? Enforce e.g. 4 spaces?
 * Default-constructing primitive types
 * Empty array expression
 * Calling functions as methods