From 73cda64c4bc34e8dec3c62a4094aa8d8ee0d246a Mon Sep 17 00:00:00 2001
From: Alejandro Mery <amery@jpi.io>
Date: Mon, 28 Aug 2023 22:56:11 +0000
Subject: [PATCH] lexer: introduce a Position (Line, Column) handler

Signed-off-by: Alejandro Mery <amery@jpi.io>
---
 lexer/position.go | 68 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 lexer/position.go

diff --git a/lexer/position.go b/lexer/position.go
new file mode 100644
index 0000000..28db23c
--- /dev/null
+++ b/lexer/position.go
@@ -0,0 +1,68 @@
+package lexer
+
+import "fmt"
+
+// Position indicates a line and column pair on a file.
+// Counting starts at 1.
+type Position struct {
+	Line   int
+	Column int
+}
+
+// String generates a pretty "(Line, Column)"" representation of the Position
+func (p Position) String() string {
+	if p.Line == 0 {
+		p.Reset()
+	}
+
+	return fmt.Sprintf("(%v, %v)", p.Line, p.Column)
+}
+
+// GoString generates a string representation of the Position for %#v usage
+func (p Position) GoString() string {
+	if p.Line == 0 {
+		p.Reset()
+	}
+
+	return fmt.Sprintf("lexer.Position{%v, %v}", p.Line, p.Column)
+}
+
+// Reset places a position at (1,1)
+func (p *Position) Reset() {
+	p.Line, p.Column = 1, 1
+}
+
+// Step moves the column one place
+func (p *Position) Step() {
+	if p.Line == 0 {
+		p.Reset()
+	}
+
+	p.Column++
+}
+
+// Next returns a new Position one rune forward
+// on the line
+func (p Position) Next() Position {
+	if p.Line == 0 {
+		p.Reset()
+	}
+
+	return Position{
+		Line:   p.Line,
+		Column: p.Column + 1,
+	}
+}
+
+// NextLine returns a new Position at the begining of the next
+// line.
+func (p Position) NextLine() Position {
+	if p.Line == 0 {
+		p.Reset()
+	}
+
+	return Position{
+		Line:   p.Line + 1,
+		Column: 1,
+	}
+}