From 6f74e4fb9cee70d5b89c64aa6c9f329e57819f11 Mon Sep 17 00:00:00 2001
From: Rangi42 <remy.oukaour+rangi42@gmail.com>
Date: Thu, 28 Mar 2024 14:49:36 -0400
Subject: [PATCH] Remove the suboptimal `.canPeek()` and `.peek()` methods

---
 include/asm/lexer.hpp |  7 -------
 src/asm/lexer.cpp     | 16 ++++++++--------
 2 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/include/asm/lexer.hpp b/include/asm/lexer.hpp
index 38e6e168..8d743aa2 100644
--- a/include/asm/lexer.hpp
+++ b/include/asm/lexer.hpp
@@ -34,8 +34,6 @@ struct Expansion {
 	size_t offset; // Cursor into `contents`
 
 	size_t size() const { return contents->size(); }
-	bool canPeek(uint8_t distance) const { return offset + distance < contents->size(); }
-	uint8_t peek(uint8_t distance) const { return (*contents)[offset + distance]; }
 	bool advance(); // Increment `offset`; return whether it then exceeds `contents`
 };
 
@@ -51,9 +49,6 @@ struct ViewedContent {
 	ViewedContent(ContentSpan const &span_) : span(span_) {}
 	ViewedContent(std::shared_ptr<char[]> ptr, size_t size) : span({.ptr = ptr, .size = size}) {}
 
-	bool canPeek(uint8_t distance) const { return offset + distance < span.size; }
-	uint8_t peek(uint8_t distance) const { return span.ptr[offset + distance]; }
-
 	std::shared_ptr<char[]> makeSharedContentPtr() const {
 		return std::shared_ptr<char[]>(span.ptr, &span.ptr[offset]);
 	}
@@ -68,8 +63,6 @@ struct BufferedContent {
 	BufferedContent(int fd_) : fd(fd_) {}
 	~BufferedContent();
 
-	bool canPeek(uint8_t distance) const { return size > distance; }
-	uint8_t peek(uint8_t distance) const { return buf[(offset + distance) % LEXER_BUF_SIZE]; }
 	void advance(); // Increment `offset` circularly, decrement `size`
 	void refill();  // Read from `fd` to fill `buf`
 
diff --git a/src/asm/lexer.cpp b/src/asm/lexer.cpp
index 8e853716..7397b51b 100644
--- a/src/asm/lexer.cpp
+++ b/src/asm/lexer.cpp
@@ -692,25 +692,25 @@ int LexerState::peek(uint8_t distance) {
 	assert(distance == 0 || distance == 1);
 
 	for (Expansion &exp : expansions) {
-		// An expansion that has reached its end will have `exp->offset` == `exp->size()`,
+		// An expansion that has reached its end will have `exp.offset` == `exp.size()`,
 		// and `.peek()` will continue with its parent
 		assert(exp.offset <= exp.size());
-		if (exp.canPeek(distance))
-			return exp.peek(distance);
+		if (exp.offset + distance < exp.size())
+			return (uint8_t)(*exp.contents)[exp.offset + distance];
 		distance -= exp.size() - exp.offset;
 	}
 
 	if (auto *view = std::get_if<ViewedContent>(&content); view) {
-		if (view->canPeek(distance))
-			return view->peek(distance);
+		if (view->offset + distance < view->span.size)
+			return (uint8_t)view->span.ptr[view->offset + distance];
 	} else {
 		assert(std::holds_alternative<BufferedContent>(content));
 		auto &cbuf = std::get<BufferedContent>(content);
 		assert(distance < LEXER_BUF_SIZE);
-		if (!cbuf.canPeek(distance))
+		if (cbuf.size <= distance)
 			cbuf.refill(); // Buffer isn't full enough, read some chars in
-		if (cbuf.canPeek(distance))
-			return cbuf.peek(distance);
+		if (cbuf.size > distance)
+			return (uint8_t)cbuf.buf[(cbuf.offset + distance) % LEXER_BUF_SIZE];
 	}
 	// If there aren't enough chars, give up
 	return EOF;