fix: fixes issue #597 - improves performance (500x faster than previous)

.version

@@ -1 +1 @@
-0.2.610
+0.2.611

parser/v2/goexpression/fuzz.sh

@@ -8,6 +8,8 @@ echo Case
 go test -fuzz=FuzzCaseStandard -fuzztime=120s
 echo Default
 go test -fuzz=FuzzCaseDefault -fuzztime=120s
+echo TemplExpression
+go test -fuzz=FuzzTemplExpression -fuzztime=120s
 echo Expression
 go test -fuzz=FuzzExpression -fuzztime=120s
 echo SliceArgs

parser/v2/goexpression/parse.go

@@ -2,11 +2,12 @@ package goexpression
 
 import (
 	"errors"
+	"fmt"
 	"go/ast"
 	"go/parser"
+	"go/scanner"
 	"go/token"
 	"regexp"
-	"slices"
 	"strings"
 	"unicode"
 )
@@ -104,56 +105,91 @@ func Switch(content string) (start, end int, err error) {
 	})
 }
 
-var boundaryTokens = map[rune]any{
-	')':  nil,
-	'}':  nil,
-	']':  nil,
-	' ':  nil,
-	'\t': nil,
-	'\n': nil,
-	'@':  nil,
-	'<':  nil,
-	'+':  nil,
-	'.':  nil,
-}
+func TemplExpression(src string) (start, end int, err error) {
+	var s scanner.Scanner
+	fset := token.NewFileSet()
+	file := fset.AddFile("", fset.Base(), len(src))
+	errorHandler := func(pos token.Position, msg string) {
+		err = fmt.Errorf("error parsing expression: %v", msg)
+	}
+	s.Init(file, []byte(src), errorHandler, 0)
 
-func allBoundaries(content string) (boundaries []int) {
-	for i, r := range content {
-		if _, ok := boundaryTokens[r]; ok {
-			boundaries = append(boundaries, i)
-			boundaries = append(boundaries, i+1)
+	// Read chains of identifiers, e.g.:
+	// components.Variable
+	// components[0].Variable
+	// components["name"].Function()
+	// functionCall(withLots(), func() { return true })
+	ep := NewExpressionParser()
+	for {
+		pos, tok, lit := s.Scan()
+		stop, err := ep.Insert(pos, tok, lit)
+		if err != nil {
+			return 0, 0, err
+		}
+		if stop {
+			break
 		}
 	}
-	boundaries = append(boundaries, len(content))
-	return
+	return 0, ep.End, nil
 }
 
-func Expression(content string) (start, end int, err error) {
-	var candidates []int
-	for _, to := range allBoundaries(content) {
-		expr, err := parser.ParseExpr(content[:to])
-		if err != nil {
-			continue
-		}
-		switch expr := expr.(type) {
-		case *ast.CallExpr:
-			end = int(expr.Rparen)
-		default:
-			end = int(expr.End()) - 1
+func Expression(src string) (start, end int, err error) {
+	var s scanner.Scanner
+	fset := token.NewFileSet()
+	file := fset.AddFile("", fset.Base(), len(src))
+	errorHandler := func(pos token.Position, msg string) {
+		err = fmt.Errorf("error parsing expression: %v", msg)
+	}
+	s.Init(file, []byte(src), errorHandler, 0)
+
+	// Read chains of identifiers and constants up until RBRACE, e.g.:
+	// true
+	// 123.45 == true
+	// components.Variable
+	// components[0].Variable
+	// components["name"].Function()
+	// functionCall(withLots(), func() { return true })
+	// !true
+	parenDepth := 0
+	bracketDepth := 0
+	braceDepth := 0
+loop:
+	for {
+		pos, tok, lit := s.Scan()
+		if tok == token.EOF {
+			break loop
 		}
-		// If the expression ends with `...` then it's a child spread expression.
-		if end < len(content) {
-			if strings.HasPrefix(content[end:], "...") {
-				end += len("...")
+		switch tok {
+		case token.LPAREN: // (
+			parenDepth++
+		case token.RPAREN: // )
+			end = int(pos)
+			parenDepth--
+		case token.LBRACK: // [
+			bracketDepth++
+		case token.RBRACK: // ]
+			end = int(pos)
+			bracketDepth--
+		case token.LBRACE: // {
+			braceDepth++
+		case token.RBRACE: // }
+			braceDepth--
+			if braceDepth < 0 {
+				// We've hit the end of the expression.
+				break loop
 			}
+			end = int(pos)
+		case token.IDENT, token.INT, token.FLOAT, token.IMAG, token.CHAR, token.STRING:
+			end = int(pos) + len(lit) - 1
+		case token.SEMICOLON:
+			continue
+		case token.ILLEGAL:
+			return 0, 0, fmt.Errorf("illegal token: %v", lit)
+		default:
+			end = int(pos) + len(tok.String()) - 1
 		}
-		candidates = append(candidates, end)
-	}
-	if len(candidates) == 0 {
-		return 0, 0, ErrExpectedNodeNotFound
 	}
-	slices.Sort(candidates)
-	return 0, candidates[len(candidates)-1], nil
+	return start, end, nil
 }
 
 func SliceArgs(content string) (expr string, err error) {

parser/v2/goexpression/parse_test.go

@@ -295,6 +295,22 @@ func FuzzCaseDefault(f *testing.F) {
 }
 
 var expressionTests = []testInput{
+	{
+		name:  "string literal",
+		input: `"hello"`,
+	},
+	{
+		name:  "string literal with escape",
+		input: `"hello\n"`,
+	},
+	{
+		name:  "backtick string literal",
+		input: "`hello`",
+	},
+	{
+		name:  "backtick string literal containing double quote",
+		input: "`hello" + `"` + `world` + "`",
+	},
 	{
 		name:  "function call in package",
 		input: `components.Other()`,
@@ -347,8 +363,6 @@ func TestExpression(t *testing.T) {
 		"}",
 		"\t}",
 		"  }",
-		"</div>",
-		"<p>/</p>",
 	}
 	for _, test := range expressionTests {
 		for i, suffix := range suffixes {
@@ -357,6 +371,94 @@ func TestExpression(t *testing.T) {
 	}
 }
 
+var templExpressionTests = []testInput{
+	{
+		name:  "function call in package",
+		input: `components.Other()`,
+	},
+	{
+		name:  "slice index call",
+		input: `components[0].Other()`,
+	},
+	{
+		name:  "map index function call",
+		input: `components["name"].Other()`,
+	},
+	{
+		name:  "map index function call backtick literal",
+		input: "components[`name" + `"` + "`].Other()",
+	},
+	{
+		name:  "function literal",
+		input: `components["name"].Other(func() bool { return true })`,
+	},
+	{
+		name: "multiline function call",
+		input: `component(map[string]string{
+				"namea": "name_a",
+			  "nameb": "name_b",
+			})`,
+	},
+	{
+		name:  "call with braces and brackets",
+		input: `templates.New(test{}, other())`,
+	},
+	{
+		name:  "struct method call",
+		input: `typeName{}.Method()`,
+	},
+	{
+		name:  "struct method call in other package",
+		input: "layout.DefaultLayout{}.Compile()",
+	},
+	{
+		name:  "bare variable",
+		input: `component`,
+	},
+}
+
+func TestTemplExpression(t *testing.T) {
+	prefix := ""
+	suffixes := []string{
+		"",
+		"}",
+		"\t}",
+		"  }",
+		"</div>",
+		"<p>/</p>",
+		" just some text",
+		" { <div>Child content</div> }",
+	}
+	for _, test := range templExpressionTests {
+		for i, suffix := range suffixes {
+			t.Run(fmt.Sprintf("%s_%d", test.name, i), run(test, prefix, suffix, TemplExpression))
+		}
+	}
+}
+
+func FuzzTemplExpression(f *testing.F) {
+	suffixes := []string{
+		"",
+		" }",
+		" }}</a>\n}",
+		"...",
+	}
+	for _, test := range expressionTests {
+		for _, suffix := range suffixes {
+			f.Add(test.input + suffix)
+		}
+	}
+	f.Fuzz(func(t *testing.T, s string) {
+		src := "switch " + s
+		start, end, err := TemplExpression(src)
+		if err != nil {
+			t.Skip()
+			return
+		}
+		panicIfInvalid(src, start, end)
+	})
+}
+
 func FuzzExpression(f *testing.F) {
 	suffixes := []string{
 		"",

parser/v2/goexpression/parsebench_test.go

@@ -0,0 +1,105 @@
+package goexpression
+
+import "testing"
+
+var testStringExpression = `"this string expression" } 
+<div>
+  But afterwards, it keeps searching.
+<div>
+
+<div>
+  But that's not right, we can stop searching. It won't find anything valid.
+</div>
+
+<div>
+  Certainly not later in the file.
+</div>
+
+<div>
+	It's going to try all the tokens.
+  )}]@<+.
+</div>
+
+<div>
+	It's going to try all the tokens.
+  )}]@<+.
+</div>
+
+<div>
+	It's going to try all the tokens.
+  )}]@<+.
+</div>
+
+<div>
+	It's going to try all the tokens.
+  )}]@<+.
+</div>
+`
+
+func BenchmarkExpression(b *testing.B) {
+	// Baseline...
+	// BenchmarkExpression-10              6484            184862 ns/op
+	// Updated...
+	// BenchmarkExpression-10           3942538               279.6 ns/op
+	for n := 0; n < b.N; n++ {
+		start, end, err := Expression(testStringExpression)
+		if err != nil {
+			b.Fatal(err)
+		}
+		if start != 0 || end != 24 {
+			b.Fatalf("expected 0, 24, got %d, %d", start, end)
+		}
+	}
+}
+
+var testTemplExpression = `templates.CallMethod(map[string]any{
+	"name": "this string expression",
+})
+
+<div>
+  But afterwards, it keeps searching.
+<div>
+
+<div>
+  But that's not right, we can stop searching. It won't find anything valid.
+</div>
+
+<div>
+  Certainly not later in the file.
+</div>
+
+<div>
+	It's going to try all the tokens.
+  )}]@<+.
+</div>
+
+<div>
+	It's going to try all the tokens.
+  )}]@<+.
+</div>
+
+<div>
+	It's going to try all the tokens.
+  )}]@<+.
+</div>
+
+<div>
+	It's going to try all the tokens.
+  )}]@<+.
+</div>
+`
+
+func BenchmarkTemplExpression(b *testing.B) {
+	// BenchmarkTemplExpression-10         2694            431934 ns/op
+	// Updated...
+	// BenchmarkTemplExpression-10      1339399               897.6 ns/op
+	for n := 0; n < b.N; n++ {
+		start, end, err := TemplExpression(testTemplExpression)
+		if err != nil {
+			b.Fatal(err)
+		}
+		if start != 0 || end != 74 {
+			b.Fatalf("expected 0, 74, got %d, %d", start, end)
+		}
+	}
+}