vendor tsgo

tools/tsgo/internal/ls/lsconv/linemap.go

@@ -0,0 +1,71 @@
+package lsconv
+
+import (
+	"cmp"
+	"slices"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/microsoft/typescript-go/internal/core"
+)
+
+type LSPLineStarts []core.TextPos
+
+type LSPLineMap struct {
+	LineStarts LSPLineStarts
+	AsciiOnly  bool // TODO(jakebailey): collect ascii-only info per line
+}
+
+func ComputeLSPLineStarts(text string) *LSPLineMap {
+	// This is like core.ComputeLineStarts, but only considers "\n", "\r", and "\r\n" as line breaks,
+	// and reports when the text is ASCII-only.
+	lineStarts := make([]core.TextPos, 0, strings.Count(text, "\n")+1)
+	asciiOnly := true
+
+	textLen := core.TextPos(len(text))
+	var pos core.TextPos
+	var lineStart core.TextPos
+	for pos < textLen {
+		b := text[pos]
+		if b < utf8.RuneSelf {
+			pos++
+			switch b {
+			case '\r':
+				if pos < textLen && text[pos] == '\n' {
+					pos++
+				}
+				fallthrough
+			case '\n':
+				lineStarts = append(lineStarts, lineStart)
+				lineStart = pos
+			}
+		} else {
+			_, size := utf8.DecodeRuneInString(text[pos:])
+			pos += core.TextPos(size)
+			asciiOnly = false
+		}
+	}
+	lineStarts = append(lineStarts, lineStart)
+
+	return &LSPLineMap{
+		LineStarts: lineStarts,
+		AsciiOnly:  asciiOnly,
+	}
+}
+
+func (lm *LSPLineMap) ComputeIndexOfLineStart(targetPos core.TextPos) int {
+	// port of computeLineOfPosition(lineStarts: readonly number[], position: number, lowerBound?: number): number {
+	lineNumber, ok := slices.BinarySearchFunc(lm.LineStarts, targetPos, func(p, t core.TextPos) int {
+		return cmp.Compare(int(p), int(t))
+	})
+	if !ok && lineNumber > 0 {
+		// If the actual position was not found, the binary search returns where the target line start would be inserted
+		// if the target was in the slice.
+		// e.g. if the line starts at [5, 10, 23, 80] and the position requested was 20
+		// then the search will return (3, false).
+		//
+		// We want the index of the previous line start, so we subtract 1.
+		lineNumber = lineNumber - 1
+	}
+	return lineNumber
+}