Code generation

cmd/ggraphqlc/dumper.go

@@ -0,0 +1,176 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+type writer struct {
+	extractor
+	out    io.Writer
+	indent int
+}
+
+func write(extractor extractor, out io.Writer) {
+	wr := writer{extractor, out, 0}
+
+	wr.writePackage()
+	wr.writeImports()
+	wr.writeInterface()
+	wr.writeResolver()
+	wr.writeSchema()
+}
+
+func (w *writer) emit(format string, args ...interface{}) {
+	io.WriteString(w.out, fmt.Sprintf(format, args...))
+}
+
+func (w *writer) emitIndent() {
+	io.WriteString(w.out, strings.Repeat("	", w.indent))
+}
+
+func (w *writer) begin(format string, args ...interface{}) {
+	w.emitIndent()
+	w.emit(format, args...)
+	w.lf()
+	w.indent++
+}
+
+func (w *writer) end(format string, args ...interface{}) {
+	w.indent--
+	w.emitIndent()
+	w.emit(format, args...)
+	w.lf()
+}
+
+func (w *writer) line(format string, args ...interface{}) {
+	w.emitIndent()
+	w.emit(format, args...)
+	w.lf()
+}
+
+func (w *writer) lf() {
+	w.out.Write([]byte("\n"))
+}
+
+func (w *writer) writePackage() {
+	w.line("package %s", w.PackageName)
+	w.lf()
+}
+
+func (w *writer) writeImports() {
+	w.begin("import (")
+	for local, pkg := range w.Imports {
+		w.line("%s %s", local, strconv.Quote(pkg))
+	}
+	w.end(")")
+	w.lf()
+}
+
+func (w *writer) writeInterface() {
+	w.begin("type Resolvers interface {")
+	for _, o := range w.Objects {
+		for _, f := range o.Fields {
+			if f.Bind != "" {
+				continue
+			}
+
+			w.emitIndent()
+			w.emit("%s_%s(", o.Name, f.Name)
+
+			first := true
+			for _, arg := range f.Args {
+				if !first {
+					w.emit(",")
+				}
+				first = false
+				w.emit("%s %s", arg.Name, arg.Type.Local())
+			}
+			w.emit(") (%s, error)", f.Type.Local())
+			w.lf()
+		}
+	}
+	w.end("}")
+	w.lf()
+}
+
+func (w *writer) writeResolver() {
+	w.begin("func NewResolver(r Resolvers) exec.Root {")
+	w.line("return &resolvers{r}")
+	w.end("}")
+	w.lf()
+
+	w.begin("type resolvers struct {")
+	w.line("resolvers Resolvers")
+	w.end("}")
+	w.lf()
+
+	for _, object := range w.Objects {
+		w.writeObjectResolver(object)
+	}
+}
+
+func (w *writer) writeObjectResolver(object object) {
+	objectName := "it"
+	if object.Type.Name != "interface{}" {
+		objectName = "object"
+	}
+
+	w.begin("func (r *resolvers) %s(ec *exec.ExecutionContext, %s interface{}, field string, arguments map[string]interface{}, sels []query.Selection) jsonw.Encodable {", object.Type.GraphQLName, objectName)
+	if object.Type.Name != "interface{}" {
+		w.line("it := object.(*%s)", object.Type.Local())
+	}
+
+	w.line("switch field {")
+
+	for _, field := range object.Fields {
+		w.begin("case %s:", strconv.Quote(field.Name))
+
+		if field.Bind != "" {
+			w.writeFieldBind(field)
+		} else {
+			w.writeFieldResolver(object, field)
+		}
+
+		w.end("")
+	}
+
+	w.line("}")
+	w.line(`panic("unknown field " + field)`)
+	w.end("}")
+	w.lf()
+}
+
+func (w *writer) writeFieldBind(field Field) {
+	w.line("return jsonw.%s(it.%s)", field.Type.GraphQLName, field.Bind)
+}
+
+func (w *writer) writeFieldResolver(object object, field Field) {
+	call := fmt.Sprintf("result, err := r.resolvers.%s_%s", object.Name, field.Name)
+	if len(field.Args) == 0 {
+		w.line(call + "()")
+	} else {
+		w.begin(call + "(")
+		for _, arg := range field.Args {
+			w.line("arguments[%s].(%s),", strconv.Quote(arg.Name), arg.Type.Local())
+		}
+		w.end(")")
+	}
+
+	w.line("if err != nil {")
+	w.line("	ec.Error(err)")
+	w.line("	return jsonw.Null")
+	w.line("}")
+
+	result := "result"
+	if !strings.HasPrefix(field.Type.Prefix, "*") {
+		result = "&result"
+	}
+	w.line("return ec.ExecuteSelectionSet(sels, r.%s, %s)", field.Type.Name, result)
+}
+
+func (w *writer) writeSchema() {
+	w.line("var Schema = schema.MustParse(%s)", strconv.Quote(w.schemaRaw))
+}