debug: Adding debugger

Fixes: open-policy-agent#6876

Signed-off-by: Johan Fylling <[email protected]>

Author: johanfylling

Diff for: debug/breakpoint.go

@@ -0,0 +1,107 @@
+// Copyright 2024 The OPA Authors.  All rights reserved.
+// Use of this source code is governed by an Apache2
+// license that can be found in the LICENSE file.
+
+package debug
+
+import (
+	"bytes"
+	"fmt"
+
+	"github.com/open-policy-agent/opa/ast/location"
+)
+
+type Breakpoint interface {
+	Id() int
+	Location() location.Location
+}
+
+type breakpoint struct {
+	id       int
+	location location.Location
+}
+
+func (b breakpoint) Id() int {
+	return b.id
+}
+
+func (b breakpoint) Location() location.Location {
+	return b.location
+}
+
+func (b breakpoint) String() string {
+	return fmt.Sprintf("<%d> %s:%d", b.id, b.location.File, b.location.Row)
+}
+
+type breakpointList []breakpoint
+
+func (b breakpointList) String() string {
+	if b == nil {
+		return "[]"
+	}
+
+	buf := new(bytes.Buffer)
+	buf.WriteString("[")
+	for i, bp := range b {
+		if i > 0 {
+			buf.WriteString(", ")
+		}
+		_, _ = fmt.Fprintf(buf, "%s:%d", bp.location.File, bp.location.Row)
+	}
+	buf.WriteString("]")
+	return buf.String()
+}
+
+type breakpointCollection struct {
+	breakpoints map[string]breakpointList
+	idCounter   int
+}
+
+func newBreakpointCollection() *breakpointCollection {
+	return &breakpointCollection{
+		breakpoints: map[string]breakpointList{},
+	}
+}
+
+func (bc *breakpointCollection) newId() int {
+	bc.idCounter++
+	return bc.idCounter
+}
+
+func (bc *breakpointCollection) add(location location.Location) Breakpoint {
+	bp := breakpoint{
+		id:       bc.newId(),
+		location: location,
+	}
+	bps := bc.breakpoints[bp.location.File]
+	bps = append(bps, bp)
+	bc.breakpoints[bp.location.File] = bps
+	return bp
+}
+
+func (bc *breakpointCollection) allForFilePath(path string) breakpointList {
+	return bc.breakpoints[path]
+}
+
+func (bc *breakpointCollection) clear() {
+	bc.breakpoints = map[string]breakpointList{}
+}
+
+func (bc *breakpointCollection) String() string {
+	if bc == nil {
+		return "[]"
+	}
+
+	buf := new(bytes.Buffer)
+	buf.WriteString("[")
+	for path, bps := range bc.breakpoints {
+		for i, bp := range bps {
+			if i > 0 {
+				buf.WriteString(", ")
+			}
+			_, _ = fmt.Fprintf(buf, "%s:%d\n", path, bp.location.Row)
+		}
+	}
+	buf.WriteString("]")
+	return buf.String()
+}