From a7612ce8736b57ca3469e272ecc74eb016ca9462 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kamil=20=C5=9Aliwak?= <kamil.sliwak@codepoets.it>
Date: Mon, 30 Aug 2021 20:06:39 +0200
Subject: [PATCH] Move the function for creating code snippets used next to
 source locations in assembly to liblangutil

---
 libevmasm/Assembly.cpp     | 12 ++----------
 liblangutil/CharStream.cpp | 16 ++++++++++++++++
 liblangutil/CharStream.h   |  9 +++++++++
 3 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/libevmasm/Assembly.cpp b/libevmasm/Assembly.cpp
index dad9635d7..c1e171221 100644
--- a/libevmasm/Assembly.cpp
+++ b/libevmasm/Assembly.cpp
@@ -31,6 +31,7 @@
 #include <libevmasm/ConstantOptimiser.h>
 #include <libevmasm/GasMeter.h>
 
+#include <liblangutil/CharStream.h>
 #include <liblangutil/Exceptions.h>
 
 #include <json/json.h>
@@ -82,16 +83,7 @@ string locationFromSources(StringMap const& _sourceCodes, SourceLocation const&
 	if (it == _sourceCodes.end())
 		return {};
 
-	string const& source = it->second;
-	if (static_cast<size_t>(_location.start) >= source.size())
-		return {};
-
-	string cut = source.substr(static_cast<size_t>(_location.start), static_cast<size_t>(_location.end - _location.start));
-	auto newLinePos = cut.find_first_of("\n");
-	if (newLinePos != string::npos)
-		cut = cut.substr(0, newLinePos) + "...";
-
-	return cut;
+	return CharStream::singleLineSnippet(it->second, _location);
 }
 
 class Functionalizer
diff --git a/liblangutil/CharStream.cpp b/liblangutil/CharStream.cpp
index 8ab99fca8..748a4a99c 100644
--- a/liblangutil/CharStream.cpp
+++ b/liblangutil/CharStream.cpp
@@ -128,3 +128,19 @@ string_view CharStream::text(SourceLocation const& _location) const
 		static_cast<size_t>(_location.end - _location.start)
 	);
 }
+
+string CharStream::singleLineSnippet(string const& _sourceCode, SourceLocation const& _location)
+{
+	if (!_location.hasText())
+		return {};
+
+	if (static_cast<size_t>(_location.start) >= _sourceCode.size())
+		return {};
+
+	string cut = _sourceCode.substr(static_cast<size_t>(_location.start), static_cast<size_t>(_location.end - _location.start));
+	auto newLinePos = cut.find_first_of("\n");
+	if (newLinePos != string::npos)
+		cut = cut.substr(0, newLinePos) + "...";
+
+	return cut;
+}
diff --git a/liblangutil/CharStream.h b/liblangutil/CharStream.h
index 4b729771f..761cece31 100644
--- a/liblangutil/CharStream.h
+++ b/liblangutil/CharStream.h
@@ -118,6 +118,15 @@ public:
 	/// Returns an empty string view if the source location does not `hasText()`.
 	std::string_view text(SourceLocation const& _location) const;
 
+	/// @returns the first line of the referenced source fragment. If the fragment is longer than
+	/// one line, appends an ellipsis to indicate that.
+	std::string singleLineSnippet(SourceLocation const& _location) const
+	{
+		return singleLineSnippet(m_source, _location);
+	}
+
+	static std::string singleLineSnippet(std::string const& _sourceCode, SourceLocation const& _location);
+
 private:
 	std::string m_source;
 	std::string m_name;