example_test.go

package applypatch_test

import (
	"fmt"
	"strings"
	"testing"

	"github.com/fgn/applypatch"
)

func ExampleApply() {
	input := "def greet():\n    print(\"Hi\")\n"
	diff := "@@ def greet():\n-    print(\"Hi\")\n+    print(\"Hello\")"
	output, err := applypatch.Apply(input, diff)
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Print(output)
	// Output:
	// def greet():
	//     print("Hello")
}

func ExampleMode_Apply() {
	// Strict mode rejects a diff that only matches when whitespace is
	// ignored; Codex mode applies it like the Codex CLI would.
	input := "total  \n"
	diff := "-total\n+sum"
	_, err := applypatch.Strict.Apply(input, diff)
	fmt.Println("strict:", err)
	output, _ := applypatch.Codex.Apply(input, diff)
	fmt.Printf("codex: %q\n", output)
	// Output:
	// strict: target must match exactly once
	// codex: "sum\n"
}

func ExampleApplyFiles() {
	files := map[string]string{"greet.py": "print(\"Hi\")\n"}
	patch := `*** Begin Patch
*** Add File: README.md
+# Greeter
*** Update File: greet.py
@@
-print("Hi")
+print("Hello")
*** End Patch`
	output, err := applypatch.Codex.ApplyFiles(files, patch)
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Printf("%q\n%q\n", output["README.md"], output["greet.py"])
	// Output:
	// "# Greeter\n"
	// "print(\"Hello\")\n"
}

func ExampleCodexTool() {
	tool := applypatch.CodexTool()
	fmt.Println(tool.Type, tool.Name, tool.Format.Type, tool.Format.Syntax)
	// Output: custom apply_patch grammar lark
}

func ExampleApplyBatch() {
	input := "alpha\nbeta\ngamma\n"
	output, err := applypatch.ApplyBatch(input, []string{"-alpha\n+ALPHA", "-gamma\n+GAMMA"})
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Print(output)
	// Output:
	// ALPHA
	// beta
	// GAMMA
}

// BenchmarkParseLargePatch guards against quadratic parsing of long updates.
func BenchmarkParseLargePatch(b *testing.B) {
	var patch strings.Builder
	patch.WriteString("*** Begin Patch\n*** Add File: big.txt\n")
	for range 20000 {
		patch.WriteString("+a line of added text\n")
	}
	patch.WriteString("*** Update File: other.txt\n@@\n")
	for range 20000 {
		patch.WriteString(" a line of context\n")
	}
	patch.WriteString("*** End Patch")
	text := patch.String()
	b.SetBytes(int64(len(text)))
	for b.Loop() {
		_, err := applypatch.Parse(text)
		if err != nil {
			b.Fatal(err)
		}
	}
}