87 lines
2.6 KiB
Go
87 lines
2.6 KiB
Go
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package main
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import (
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"encoding/xml"
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"log"
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)
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type XMLField struct {
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XMLName xml.Name
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// For 'pad' element
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Bytes uint `xml:"bytes,attr"`
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Align uint16 `xml:"align,attr"`
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// For 'field', 'list', 'localfield', 'exprfield' and 'switch' elements.
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Name string `xml:"name,attr"`
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// For 'field', 'list', 'localfield', and 'exprfield' elements.
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Type string `xml:"type,attr"`
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// For 'list', 'exprfield' and 'switch' elements.
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Expr *XMLExpression `xml:",any"`
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// For 'valueparm' element.
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ValueMaskType string `xml:"value-mask-type,attr"`
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ValueMaskName string `xml:"value-mask-name,attr"`
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ValueListName string `xml:"value-list-name,attr"`
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// For 'switch' element.
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Bitcases []*XMLBitcase `xml:"bitcase"`
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// I don't know which elements these are for. The documentation is vague.
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// They also seem to be completely optional.
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OptEnum string `xml:"enum,attr"`
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OptMask string `xml:"mask,attr"`
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OptAltEnum string `xml:"altenum,attr"`
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}
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// Bitcase represents a single expression followed by any number of fields.
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// Namely, if the switch's expression (all bitcases are inside a switch),
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// and'd with the bitcase's expression is equal to the bitcase expression,
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// then the fields should be included in its parent structure.
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// Note that since a bitcase is unique in that expressions and fields are
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// siblings, we must exhaustively search for one of them. Essentially,
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// it's the closest thing to a Union I can get to in Go without interfaces.
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// Would an '<expression>' tag have been too much to ask? :-(
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type XMLBitcase struct {
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Fields []*XMLField `xml:",any"`
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// All the different expressions.
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// When it comes time to choose one, use the 'Expr' method.
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ExprOp *XMLExpression `xml:"op"`
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ExprUnOp *XMLExpression `xml:"unop"`
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ExprField *XMLExpression `xml:"fieldref"`
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ExprValue *XMLExpression `xml:"value"`
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ExprBit *XMLExpression `xml:"bit"`
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ExprEnum *XMLExpression `xml:"enumref"`
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ExprSum *XMLExpression `xml:"sumof"`
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ExprPop *XMLExpression `xml:"popcount"`
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}
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// Expr chooses the only non-nil Expr* field from Bitcase.
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// Panic if there is more than one non-nil expression.
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func (b *XMLBitcase) Expr() *XMLExpression {
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choices := []*XMLExpression{
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b.ExprOp, b.ExprUnOp, b.ExprField, b.ExprValue,
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b.ExprBit, b.ExprEnum, b.ExprSum, b.ExprPop,
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}
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var choice *XMLExpression = nil
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numNonNil := 0
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for _, c := range choices {
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if c != nil {
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numNonNil++
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choice = c
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}
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}
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if choice == nil {
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log.Panicf("No top level expression found in a bitcase.")
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}
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if numNonNil > 1 {
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log.Panicf("More than one top-level expression was found in a bitcase.")
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}
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return choice
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}
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