From 5a3d2778250bd5a64985d3b13771dbc9ef5bd739 Mon Sep 17 00:00:00 2001
From: arikkfir <arik@kfirs.com>
Date: Mon, 24 Nov 2025 14:54:31 +0200
Subject: [PATCH] feat: Support fixed-length source code

This change adds support for fixed-length source code field rendering, with smart-trimming that keeps the start & end section, with `...` replacing the part that gets removed.

Configuration:
```go
handler = console.NewHandler(os.Stdout, &console.HandlerOptions{
	SourceLength: 20,
})
```

Examples (max-length 20):
```
Source: 1234567890                      -> 10:00PM INF 1234567890           > Some log line
Source: pkgA/pkgB/jack_the_knife.go:123 -> 10:00PM INF pkgA/pkg...fe.go:123 > Another log line
Source: testing/superlogs.go:12         -> 10:00PM INF testing/...ogs.go:12 > Yet another log line
```
---
 encoding.go | 23 ++++++++++++++++++++---
 handler.go  |  5 +++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/encoding.go b/encoding.go
index 6088e65..8903479 100644
--- a/encoding.go
+++ b/encoding.go
@@ -5,6 +5,7 @@ import (
 	"log/slog"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"time"
 )
 
@@ -83,9 +84,25 @@ func (e encoder) writeSource(buf *buffer, pc uintptr, cwd string) {
 		}
 	}
 	e.withColor(buf, e.opts.Theme.Source(), func() {
-		buf.AppendString(frame.File)
-		buf.AppendByte(':')
-		buf.AppendInt(int64(frame.Line))
+		if e.opts.SourceLength > 0 {
+			source := fmt.Sprintf("%s:%d", frame.File, frame.Line)
+			if len(source) > e.opts.SourceLength {
+				charsThatFit := e.opts.SourceLength - 3
+				frontChars := source[:charsThatFit/2]
+				if charsThatFit%2 == 1 {
+					charsThatFit = charsThatFit + 1
+				}
+				rearChars := source[len(source)-charsThatFit/2:]
+				source = frontChars + "..." + rearChars
+			} else {
+				source = source + strings.Repeat(" ", e.opts.SourceLength-len(source))
+			}
+			buf.AppendString(source)
+		} else {
+			buf.AppendString(frame.File)
+			buf.AppendByte(':')
+			buf.AppendInt(int64(frame.Line))
+		}
 	})
 	e.writeColoredString(buf, " > ", e.opts.Theme.AttrKey())
 }
diff --git a/handler.go b/handler.go
index 82ce3ea..1edc314 100644
--- a/handler.go
+++ b/handler.go
@@ -33,6 +33,11 @@ type HandlerOptions struct {
 	// Disable colorized output
 	NoColor bool
 
+	// Enforce a fixed length for the source code field. If set, source code references longer than the field value
+	// will be trimmed but retain their starting & ending characters. If the source code is shorter than the set value,
+	// it is padded with spaces.
+	SourceLength int
+
 	// TimeFormat is the format used for time.DateTime
 	TimeFormat string