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package main
import (
"bytes"
"encoding/xml"
"fmt"
"log"
"sort"
"strings"
)
// Context represents the protocol we're converting to Go, and a writer
// buffer to write the Go source to.
type Context struct {
protocol *Protocol
out *bytes.Buffer
}
func newContext() *Context {
return &Context{
out: bytes.NewBuffer([]byte{}),
}
}
// Putln calls put and adds a new line to the end of 'format'.
func (c *Context) Putln(format string, v ...interface{}) {
c.Put(format+"\n", v...)
}
// Put is a short alias to write to 'out'.
func (c *Context) Put(format string, v ...interface{}) {
_, err := c.out.WriteString(fmt.Sprintf(format, v...))
if err != nil {
log.Fatalf("There was an error writing to context buffer: %s", err)
}
}
// PutComment writes each line of comment commented out to 'out'.
func (c *Context) PutComment(comment string) {
for _, line := range strings.Split(comment, "\n") {
c.Putln("// %s", line)
}
}
// Morph is the big daddy of them all. It takes in an XML byte slice,
// parse it, transforms the XML types into more usable types,
// and writes Go code to the 'out' buffer.
func (c *Context) Morph(xmlBytes []byte) {
parsedXml := &XML{}
err := xml.Unmarshal(xmlBytes, parsedXml)
if err != nil {
log.Fatal(err)
}
// Parse all imports
parsedXml.Imports.Eval()
// Translate XML types to nice types
c.protocol = parsedXml.Translate(nil)
// For backwards compatibility we patch the type of the send_event field of
// PutImage to be byte
if c.protocol.Name == "shm" {
for _, req := range c.protocol.Requests {
if req.xmlName != "PutImage" {
continue
}
for _, ifield := range req.Fields {
field, ok := ifield.(*SingleField)
if !ok || field.xmlName != "send_event" {
continue
}
field.Type = &Base{srcName: "byte", xmlName: "CARD8", size: newFixedSize(1, true)}
}
}
}
// Start with Go header.
c.Putln("// Package %s is the X client API for the %s extension.",
c.protocol.PkgName(), c.protocol.ExtXName)
c.Putln("package %s", c.protocol.PkgName())
c.Putln("")
c.Putln("// This file is automatically generated from %s.xml. "+
"Edit at your peril!", c.protocol.Name)
c.Putln("")
// Write imports. We always need to import at least xgb.
// We also need to import xproto if it's an extension.
c.Putln("import (")
c.Putln("xgb \"janouch.name/haven/nexgb\"")
c.Putln("")
if c.protocol.isExt() {
c.Putln("\"janouch.name/haven/nexgb/xproto\"")
}
sort.Sort(Protocols(c.protocol.Imports))
for _, imp := range c.protocol.Imports {
// We always import xproto, so skip it if it's explicitly imported
if imp.Name == "xproto" {
continue
}
c.Putln("\"janouch.name/haven/nexgb/%s\"", imp.Name)
}
c.Putln(")")
c.Putln("")
// If this is an extension, create a function to initialize the extension
// before it can be used.
if c.protocol.isExt() {
xname := c.protocol.ExtXName
c.Putln("const (")
c.Putln("MajorVersion = %s", c.protocol.MajorVersion)
c.Putln("MinorVersion = %s", c.protocol.MinorVersion)
c.Putln(")")
c.Putln("")
c.Putln("// Init must be called before using the %s extension.",
xname)
c.Putln("func Init(c *xgb.Conn) error {")
c.Putln("reply, err := xproto.QueryExtension(c, %d, \"%s\").Reply()",
len(xname), xname)
c.Putln("switch {")
c.Putln("case err != nil:")
c.Putln("return err")
c.Putln("case !reply.Present:")
c.Putln("return xgb.Errorf(\"No extension named %s could be found on "+
"on the server.\")", xname)
c.Putln("}")
c.Putln("")
c.Putln("c.ExtLock.Lock()")
c.Putln("c.Extensions[\"%s\"] = reply.MajorOpcode", xname)
c.Putln("c.ExtLock.Unlock()")
c.Putln("for evNum, fun := range xgb.NewExtEventFuncs[\"%s\"] {",
xname)
c.Putln("xgb.NewEventFuncs[int(reply.FirstEvent) + evNum] = fun")
c.Putln("}")
c.Putln("for errNum, fun := range xgb.NewExtErrorFuncs[\"%s\"] {",
xname)
c.Putln("xgb.NewErrorFuncs[int(reply.FirstError) + errNum] = fun")
c.Putln("}")
c.Putln("return nil")
c.Putln("}")
c.Putln("")
// Make sure newExtEventFuncs["EXT_NAME"] map is initialized.
// Same deal for newExtErrorFuncs["EXT_NAME"]
c.Putln("func init() {")
c.Putln("xgb.NewExtEventFuncs[\"%s\"] = make(map[int]xgb.NewEventFun)",
xname)
c.Putln("xgb.NewExtErrorFuncs[\"%s\"] = make(map[int]xgb.NewErrorFun)",
xname)
c.Putln("}")
c.Putln("")
} else {
// In the xproto package, we must provide a Setup function that uses
// SetupBytes in xgb.Conn to return a SetupInfo structure.
c.Putln("// Setup parses the setup bytes retrieved when")
c.Putln("// connecting into a SetupInfo struct.")
c.Putln("func Setup(c *xgb.Conn) *SetupInfo {")
c.Putln("setup := new(SetupInfo)")
c.Putln("SetupInfoRead(c.SetupBytes, setup)")
c.Putln("return setup")
c.Putln("}")
c.Putln("")
c.Putln("// DefaultScreen gets the default screen info from SetupInfo.")
c.Putln("func (s *SetupInfo) DefaultScreen(c *xgb.Conn) *ScreenInfo {")
c.Putln("return &s.Roots[c.DefaultScreen]")
c.Putln("}")
c.Putln("")
}
// Now write Go source code
sort.Sort(Types(c.protocol.Types))
sort.Sort(Requests(c.protocol.Requests))
for _, typ := range c.protocol.Types {
typ.Define(c)
}
for _, req := range c.protocol.Requests {
req.Define(c)
}
}
|
