internal/go/gen: Ident type

internal/go/gen/ident.go

@@ -0,0 +1,41 @@
+package gen
+
+import (
+	"strings"
+)
+
+// Ident represents a qualified Go identifier. It is a combination of
+// a package path and a short name. For package identifiers, Path
+// represents the package path (e.g. "encoding/json") and Name
+// represents the short package name (e.g. "json").
+type Ident struct {
+	Path string
+	Name string
+}
+
+// ParseIdent parses string s into an [Ident].
+// It returns an error if s cannot be successfully parsed
+func ParseIdent(s string) (Ident, error) {
+	var id Ident
+	id.Path, id.Name, _ = strings.Cut(s, "#")
+	if id.Name == "" {
+		i := strings.LastIndex(id.Path, "/")
+		if i >= 0 && i < len(id.Path)-1 {
+			id.Name = id.Path[i+1:] // encoding/json -> json
+		} else {
+			id.Name = id.Path // encoding -> encoding
+		}
+	}
+	return id, nil
+}
+
+// String returns the canonical string representation of id. It implements the [fmt.Stringer] interface.
+//
+// The canonical string representation of an [Ident] is "$path#$name". Examples:
+//   - For a package: "encoding/xml#xml"
+//   - For a type: "encoding/xml#Attr"
+//   - For a constant: "encoding/xml#Header"
+//   - For a function: "encoding/xml#Marshal"
+func (id Ident) String() string {
+	return id.Path + "#" + id.Name
+}

internal/go/gen/ident_test.go

@@ -0,0 +1,38 @@
+package gen
+
+import "testing"
+
+func TestParseIdent(t *testing.T) {
+	tests := []struct {
+		s       string
+		want    Ident
+		wantErr bool
+	}{
+		{"io", Ident{"io", "io"}, false},
+		{"io/fs", Ident{"io/fs", "fs"}, false},
+		{"encoding/json", Ident{"encoding/json", "json"}, false},
+		{"encoding/xml", Ident{"encoding/xml", "xml"}, false},
+		{"encoding/xml#xml", Ident{"encoding/xml", "xml"}, false},
+		{"encoding/xml#encxml", Ident{"encoding/xml", "encxml"}, false},
+		{"encoding/xml#Encoder", Ident{"encoding/xml", "Encoder"}, false},
+		{"encoding/xml#Decoder", Ident{"encoding/xml", "Decoder"}, false},
+		{"wasi/clocks", Ident{"wasi/clocks", "clocks"}, false},
+		{"wasi/clocks#clocks", Ident{"wasi/clocks", "clocks"}, false},
+		{"wasi/clocks/wallclock", Ident{"wasi/clocks/wallclock", "wallclock"}, false},
+		{"wasi/clocks/wallclock#wallclock", Ident{"wasi/clocks/wallclock", "wallclock"}, false},
+		{"wasi/clocks/wallclock#DateTime", Ident{"wasi/clocks/wallclock", "DateTime"}, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.s, func(t *testing.T) {
+			got, err := ParseIdent(tt.s)
+			if tt.wantErr && err == nil {
+				t.Errorf("ParseIdent(%q): expected error, got nil error", tt.s)
+			} else if !tt.wantErr && err != nil {
+				t.Errorf("ParseIdent(%q): expected no error, got error: %v", tt.s, err)
+			}
+			if got != tt.want {
+				t.Errorf("ParseIdent(%q): expected %v, got %v", tt.s, tt.want, got)
+			}
+		})
+	}
+}