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package main
import (
"encoding/xml"
"log"
)
type XMLField struct {
XMLName xml.Name
// For 'pad' element
Bytes uint `xml:"bytes,attr"`
// For 'field', 'list', 'localfield', 'exprfield' and 'switch' elements.
Name string `xml:"name,attr"`
// For 'field', 'list', 'localfield', and 'exprfield' elements.
Type string `xml:"type,attr"`
// For 'list', 'exprfield' and 'switch' elements.
Expr *XMLExpression `xml:",any"`
// For 'valueparm' element.
ValueMaskType string `xml:"value-mask-type,attr"`
ValueMaskName string `xml:"value-mask-name,attr"`
ValueListName string `xml:"value-list-name,attr"`
// For 'switch' element.
Bitcases []*XMLBitcase `xml:"bitcase"`
// I don't know which elements these are for. The documentation is vague.
// They also seem to be completely optional.
OptEnum string `xml:"enum,attr"`
OptMask string `xml:"mask,attr"`
OptAltEnum string `xml:"altenum,attr"`
}
// Bitcase represents a single expression followed by any number of fields.
// Namely, if the switch's expression (all bitcases are inside a switch),
// and'd with the bitcase's expression is equal to the bitcase expression,
// then the fields should be included in its parent structure.
// Note that since a bitcase is unique in that expressions and fields are
// siblings, we must exhaustively search for one of them. Essentially,
// it's the closest thing to a Union I can get to in Go without interfaces.
// Would an '<expression>' tag have been too much to ask? :-(
type XMLBitcase struct {
Fields []*XMLField `xml:",any"`
// All the different expressions.
// When it comes time to choose one, use the 'Expr' method.
ExprOp *XMLExpression `xml:"op"`
ExprUnOp *XMLExpression `xml:"unop"`
ExprField *XMLExpression `xml:"fieldref"`
ExprValue *XMLExpression `xml:"value"`
ExprBit *XMLExpression `xml:"bit"`
ExprEnum *XMLExpression `xml:"enumref"`
ExprSum *XMLExpression `xml:"sumof"`
ExprPop *XMLExpression `xml:"popcount"`
}
// Expr chooses the only non-nil Expr* field from Bitcase.
// Panic if there is more than one non-nil expression.
func (b *XMLBitcase) Expr() *XMLExpression {
choices := []*XMLExpression{
b.ExprOp, b.ExprUnOp, b.ExprField, b.ExprValue,
b.ExprBit, b.ExprEnum, b.ExprSum, b.ExprPop,
}
var choice *XMLExpression = nil
numNonNil := 0
for _, c := range choices {
if c != nil {
numNonNil++
choice = c
}
}
if choice == nil {
log.Panicf("No top level expression found in a bitcase.")
}
if numNonNil > 1 {
log.Panicf("More than one top-level expression was found in a bitcase.")
}
return choice
}
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