feat: re-use line offsets from sourcemapping logic

internal/printer/print-to-tsx.go

@@ -13,7 +13,6 @@ import (
 	"github.com/withastro/compiler/internal/loc"
 	"github.com/withastro/compiler/internal/sourcemap"
 	"github.com/withastro/compiler/internal/transform"
-	esbuild "github.com/withastro/compiler/lib/esbuild/helpers"
 	"golang.org/x/net/html/atom"
 )
 
@@ -38,13 +37,26 @@ func PrintToTSX(sourcetext string, n *Node, opts TSXOptions, transformOpts trans
 	return PrintResult{
 		Output:         p.output,
 		SourceMapChunk: p.builder.GenerateChunk(p.output),
-		TSXRanges:      p.ranges,
+		TSXRanges:      finalizeRanges(string(p.output), p.ranges),
 	}
 }
 
-func getUTF16Length(s string) int {
-	// Go has a built-in module for utf16, but esbuild's is faster and slightly more friendly
-	return len(esbuild.StringToUTF16(s))
+func finalizeRanges(content string, ranges TSXRanges) TSXRanges {
+	chunkBuilder := sourcemap.MakeChunkBuilder(nil, sourcemap.GenerateLineOffsetTables(content, len(strings.Split(content, "\n"))))
+
+	return TSXRanges{
+		Frontmatter: loc.TSXRange{
+			Start: chunkBuilder.OffsetAt(loc.Loc{Start: ranges.Frontmatter.Start}),
+			End:   chunkBuilder.OffsetAt(loc.Loc{Start: ranges.Frontmatter.End}),
+		},
+		Body: loc.TSXRange{
+			Start: chunkBuilder.OffsetAt(loc.Loc{Start: ranges.Body.Start}),
+			End:   chunkBuilder.OffsetAt(loc.Loc{Start: ranges.Body.End}),
+		},
+		// Scripts and styles are already using the proper positions
+		Scripts: ranges.Scripts,
+		Styles:  ranges.Styles,
+	}
 }
 
 type TSXRanges struct {
@@ -324,7 +336,7 @@ func renderTsx(p *printer, n *Node, o *TSXOptions) {
 		props := js_scanner.GetPropsType(source)
 		hasGetStaticPaths := js_scanner.HasGetStaticPaths(source)
 		hasChildren := false
-		startLoc := getUTF16Length(string(p.output))
+		startLen := len(p.output)
 		for c := n.FirstChild; c != nil; c = c.NextSibling {
 			// This checks for the first node that comes *after* the frontmatter
 			// to ensure that the statement is properly closed with a `;`.
@@ -344,15 +356,15 @@ func renderTsx(p *printer, n *Node, o *TSXOptions) {
 				p.print("<Fragment>\n")
 
 				// Update the start location of the body to the start of the first child
-				startLoc = getUTF16Length(string(p.output))
+				startLen = len(p.output)
 
 				hasChildren = true
 			}
 			if c.PrevSibling == nil && c.Type != FrontmatterNode {
 				p.addNilSourceMapping()
 				p.print("<Fragment>\n")
 
-				startLoc = getUTF16Length(string(p.output))
+				startLen = len(p.output)
 
 				hasChildren = true
 			}
@@ -363,8 +375,8 @@ func renderTsx(p *printer, n *Node, o *TSXOptions) {
 
 		p.addNilSourceMapping()
 		p.setTSXBodyRange(loc.TSXRange{
-			Start: startLoc,
-			End:   getUTF16Length(string(p.output)),
+			Start: startLen,
+			End:   len(p.output),
 		})
 
 		// Only close the body with `</Fragment>` if we printed a body
@@ -407,7 +419,7 @@ declare const Astro: Readonly<import('astro').AstroGlobal<%s, typeof %s`, propsI
 
 	if n.Type == FrontmatterNode {
 		p.addSourceMapping(loc.Loc{Start: 0})
-		frontmatterStart := getUTF16Length(string(p.output))
+		frontmatterStart := len(p.output)
 		for c := n.FirstChild; c != nil; c = c.NextSibling {
 			if c.Type == TextNode {
 				if len(c.Loc) > 0 {
@@ -426,7 +438,7 @@ declare const Astro: Readonly<import('astro').AstroGlobal<%s, typeof %s`, propsI
 		}
 		p.setTSXFrontmatterRange(loc.TSXRange{
 			Start: frontmatterStart,
-			End:   getUTF16Length(string(p.output)),
+			End:   len(p.output),
 		})
 		return
 	}
@@ -576,10 +588,10 @@ declare const Astro: Readonly<import('astro').AstroGlobal<%s, typeof %s`, propsI
 			}
 
 			if _, ok := htmlEvents[a.Key]; ok {
-				p.addTSXScript(getUTF16Length(p.sourcetext[:a.ValLoc.Start]), getUTF16Length(p.sourcetext[:endLoc]), a.Val, "event-attribute")
+				p.addTSXScript(p.builder.OffsetAt(a.ValLoc), p.builder.OffsetAt(loc.Loc{Start: endLoc}), a.Val, "event-attribute")
 			}
 			if a.Key == "style" {
-				p.addTSXStyle(getUTF16Length(p.sourcetext[:a.ValLoc.Start]), getUTF16Length(p.sourcetext[:endLoc]), a.Val, "style-attribute", "css")
+				p.addTSXStyle(p.builder.OffsetAt(a.ValLoc), p.builder.OffsetAt(loc.Loc{Start: endLoc}), a.Val, "style-attribute", "css")
 			}
 		case astro.EmptyAttribute:
 			p.print(a.Key)
@@ -742,7 +754,7 @@ declare const Astro: Readonly<import('astro').AstroGlobal<%s, typeof %s`, propsI
 	}
 	p.print(">")
 
-	contentToStartTagEnd := p.sourcetext[:endLoc]
+	startTagEndLoc := loc.Loc{Start: endLoc}
 
 	// Render any child nodes
 	for c := n.FirstChild; c != nil; c = c.NextSibling {
@@ -763,16 +775,15 @@ declare const Astro: Readonly<import('astro').AstroGlobal<%s, typeof %s`, propsI
 	}
 
 	if n.FirstChild != nil && (n.DataAtom == atom.Script || n.DataAtom == atom.Style) {
-		maxLength := endLoc
+		tagContentEndLoc := loc.Loc{Start: endLoc}
 		if endLoc > len(p.sourcetext) { // Sometimes, when tags are not closed properly, endLoc can be greater than the length of the source text, wonky stuff
-			maxLength = len(p.sourcetext)
+			tagContentEndLoc.Start = len(p.sourcetext)
 		}
-		contentToContentEnd := p.sourcetext[:maxLength]
 		if n.DataAtom == atom.Script {
-			p.addTSXScript(getUTF16Length(contentToStartTagEnd), getUTF16Length(contentToContentEnd), n.FirstChild.Data, getScriptTypeFromAttrs(n.Attr))
+			p.addTSXScript(p.builder.OffsetAt(startTagEndLoc), p.builder.OffsetAt(tagContentEndLoc), n.FirstChild.Data, getScriptTypeFromAttrs(n.Attr))
 		}
 		if n.DataAtom == atom.Style {
-			p.addTSXStyle(getUTF16Length(contentToStartTagEnd), getUTF16Length(contentToContentEnd), n.FirstChild.Data, "tag", getStyleLangFromAttrs(n.Attr))
+			p.addTSXStyle(p.builder.OffsetAt(startTagEndLoc), p.builder.OffsetAt(tagContentEndLoc), n.FirstChild.Data, "tag", getStyleLangFromAttrs(n.Attr))
 		}
 	}