[chore] Update gin to v1.9.0 (#1553)

vendor/github.com/twitchyliquid64/golang-asm/src/xpos.go

@@ -0,0 +1,176 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file implements the compressed encoding of source
+// positions using a lookup table.
+
+package src
+
+// XPos is a more compact representation of Pos.
+type XPos struct {
+	index int32
+	lico
+}
+
+// NoXPos is a valid unknown position.
+var NoXPos XPos
+
+// IsKnown reports whether the position p is known.
+// XPos.IsKnown() matches Pos.IsKnown() for corresponding
+// positions.
+func (p XPos) IsKnown() bool {
+	return p.index != 0 || p.Line() != 0
+}
+
+// Before reports whether the position p comes before q in the source.
+// For positions with different bases, ordering is by base index.
+func (p XPos) Before(q XPos) bool {
+	n, m := p.index, q.index
+	return n < m || n == m && p.lico < q.lico
+}
+
+// SameFile reports whether p and q are positions in the same file.
+func (p XPos) SameFile(q XPos) bool {
+	return p.index == q.index
+}
+
+// SameFileAndLine reports whether p and q are positions on the same line in the same file.
+func (p XPos) SameFileAndLine(q XPos) bool {
+	return p.index == q.index && p.lico.SameLine(q.lico)
+}
+
+// After reports whether the position p comes after q in the source.
+// For positions with different bases, ordering is by base index.
+func (p XPos) After(q XPos) bool {
+	n, m := p.index, q.index
+	return n > m || n == m && p.lico > q.lico
+}
+
+// WithNotStmt returns the same location to be marked with DWARF is_stmt=0
+func (p XPos) WithNotStmt() XPos {
+	p.lico = p.lico.withNotStmt()
+	return p
+}
+
+// WithDefaultStmt returns the same location with undetermined is_stmt
+func (p XPos) WithDefaultStmt() XPos {
+	p.lico = p.lico.withDefaultStmt()
+	return p
+}
+
+// WithIsStmt returns the same location to be marked with DWARF is_stmt=1
+func (p XPos) WithIsStmt() XPos {
+	p.lico = p.lico.withIsStmt()
+	return p
+}
+
+// WithBogusLine returns a bogus line that won't match any recorded for the source code.
+// Its use is to disrupt the statements within an infinite loop so that the debugger
+// will not itself loop infinitely waiting for the line number to change.
+// gdb chooses not to display the bogus line; delve shows it with a complaint, but the
+// alternative behavior is to hang.
+func (p XPos) WithBogusLine() XPos {
+	if p.index == 0 {
+		// See #35652
+		panic("Assigning a bogus line to XPos with no file will cause mysterious downstream failures.")
+	}
+	p.lico = makeBogusLico()
+	return p
+}
+
+// WithXlogue returns the same location but marked with DWARF function prologue/epilogue
+func (p XPos) WithXlogue(x PosXlogue) XPos {
+	p.lico = p.lico.withXlogue(x)
+	return p
+}
+
+// LineNumber returns a string for the line number, "?" if it is not known.
+func (p XPos) LineNumber() string {
+	if !p.IsKnown() {
+		return "?"
+	}
+	return p.lico.lineNumber()
+}
+
+// FileIndex returns a smallish non-negative integer corresponding to the
+// file for this source position.  Smallish is relative; it can be thousands
+// large, but not millions.
+func (p XPos) FileIndex() int32 {
+	return p.index
+}
+
+func (p XPos) LineNumberHTML() string {
+	if !p.IsKnown() {
+		return "?"
+	}
+	return p.lico.lineNumberHTML()
+}
+
+// AtColumn1 returns the same location but shifted to column 1.
+func (p XPos) AtColumn1() XPos {
+	p.lico = p.lico.atColumn1()
+	return p
+}
+
+// A PosTable tracks Pos -> XPos conversions and vice versa.
+// Its zero value is a ready-to-use PosTable.
+type PosTable struct {
+	baseList []*PosBase
+	indexMap map[*PosBase]int
+	nameMap  map[string]int // Maps file symbol name to index for debug information.
+}
+
+// XPos returns the corresponding XPos for the given pos,
+// adding pos to t if necessary.
+func (t *PosTable) XPos(pos Pos) XPos {
+	m := t.indexMap
+	if m == nil {
+		// Create new list and map and populate with nil
+		// base so that NoPos always gets index 0.
+		t.baseList = append(t.baseList, nil)
+		m = map[*PosBase]int{nil: 0}
+		t.indexMap = m
+		t.nameMap = make(map[string]int)
+	}
+	i, ok := m[pos.base]
+	if !ok {
+		i = len(t.baseList)
+		t.baseList = append(t.baseList, pos.base)
+		t.indexMap[pos.base] = i
+		if _, ok := t.nameMap[pos.base.symFilename]; !ok {
+			t.nameMap[pos.base.symFilename] = len(t.nameMap)
+		}
+	}
+	return XPos{int32(i), pos.lico}
+}
+
+// Pos returns the corresponding Pos for the given p.
+// If p cannot be translated via t, the function panics.
+func (t *PosTable) Pos(p XPos) Pos {
+	var base *PosBase
+	if p.index != 0 {
+		base = t.baseList[p.index]
+	}
+	return Pos{base, p.lico}
+}
+
+// FileIndex returns the index of the given filename(symbol) in the PosTable, or -1 if not found.
+func (t *PosTable) FileIndex(filename string) int {
+	if v, ok := t.nameMap[filename]; ok {
+		return v
+	}
+	return -1
+}
+
+// FileTable returns a slice of all files used to build this package.
+func (t *PosTable) FileTable() []string {
+	// Create a LUT of the global package level file indices. This table is what
+	// is written in the debug_lines header, the file[N] will be referenced as
+	// N+1 in the debug_lines table.
+	fileLUT := make([]string, len(t.nameMap))
+	for str, i := range t.nameMap {
+		fileLUT[i] = str
+	}
+	return fileLUT
+}