haven/nexgb/xgbgen/context.go

119 lines
3.1 KiB
Go

package main
import (
"bytes"
"encoding/xml"
"fmt"
"log"
"strings"
"time"
)
// 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)
}
}
// 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()
// Start with Go header.
c.Putln("package xgb")
c.Putln("")
c.Putln("/*")
c.Putln("\tThis file was generated by %s.xml on %s.",
c.protocol.Name, time.Now().Format("Jan 2 2006 3:04:05pm MST"))
c.Putln("\tThis file is automatically generated. Edit at your peril!")
c.Putln("*/")
c.Putln("")
// Write imports in comments
if len(c.protocol.Imports) > 0 {
c.Putln("// Imports are not necessary for XGB because everything is ")
c.Putln("// in one package. They are still listed here for reference.")
for _, imp := range c.protocol.Imports {
c.Putln("// import \"%s\"", imp.Name)
}
c.Putln("")
}
// If this is an extension, create a function to initialize the extension
// before it can be used.
if c.protocol.isExt() {
name := strings.Title(c.protocol.Name) + "Init"
xname := c.protocol.ExtXName
c.Putln("// %s must be called before using the %s extension.",
name, xname)
c.Putln("func (c *Conn) %s() error {", name)
c.Putln("reply, err := c.QueryExtension(%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 newError(\"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("for evNum, fun := range newExtEventFuncs[\"%s\"] {", xname)
c.Putln("newEventFuncs[int(reply.FirstEvent) + evNum] = fun")
c.Putln("}")
c.Putln("c.extLock.Unlock()")
c.Putln("")
c.Putln("return nil")
c.Putln("}")
c.Putln("")
// Make sure newExtEventFuncs["EXT_NAME"] map is initialized.
c.Putln("func init() {")
c.Putln("newExtEventFuncs[\"%s\"] = make(map[int]newEventFun)", xname)
c.Putln("}")
c.Putln("")
}
// Now write Go source code
for _, typ := range c.protocol.Types {
typ.Define(c)
}
for _, req := range c.protocol.Requests {
req.Define(c)
}
}