/
codex.go
262 lines (246 loc) · 9.16 KB
/
codex.go
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// Copyright 2021 Aaron Moss
// Copyright 2019 Marius Ackerman
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package gll
import (
"bytes"
"text/template"
"github.com/bruceiv/pegll/ast"
"github.com/bruceiv/pegll/gslot"
)
func (g *gen) genAlternatesCode() string {
buf := new(bytes.Buffer)
for _, nt := range g.g.NonTerminals.ElementsSorted() {
buf.WriteString(g.getRuleCode(nt))
}
return buf.String()
}
const (
ordered = true
unordered = false
)
func (g *gen) getRuleCode(nt string) string {
buf := new(bytes.Buffer)
rule := g.g.GetSyntaxRule(nt)
if rule.IsOrdered || len(rule.Alternates) == 1 {
// try alternates one-at-a-time if ordered or only one
for i, alt := range rule.Alternates {
buf.WriteString(g.getAlternateCode(nt, alt, i, len(rule.Alternates), ordered))
}
} else {
// double-generate alternates of unordered rules to encode
// match status in rule labels
for i, alt := range rule.Alternates {
buf.WriteString(g.getAlternateCode(nt, alt, i, len(rule.Alternates), unordered))
}
}
// finish with failure alternate for all nonterminals that don't end with an empty alternate
if !rule.AlwaysMatches() {
buf.WriteString(g.getFailAlternate(nt, len(rule.Alternates)))
}
return buf.String()
}
type AltData struct {
NT string
AltLabel string
PassAltLabel string
AltComment string
HasPass bool
Slots []*SlotData
LastSlot *SlotData
}
func (g *gen) getAlternateCode(nt string, alt *ast.SyntaxAlternate, altI, altN int, isOrdered bool) string {
// fmt.Printf("codes.genAlternateCode: %s altI %d\n", nt, altI)
var tmpl *template.Template
var err error
if alt.Empty() {
tmpl, err = template.New("EmptyAlternate").Parse(eAltCodeTmpl)
} else if isOrdered {
tmpl, err = template.New("OrderedAlternate").Parse(oAltCodeTmpl)
} else {
tmpl, err = template.New("UnorderedAlternate").Parse(uAltCodeTmpl)
}
if err != nil {
panic(err)
}
buf, data := new(bytes.Buffer), g.getAltData(nt, alt, altI, altN, isOrdered)
if err = tmpl.Execute(buf, data); err != nil {
panic(err)
}
return buf.String()
}
func (g *gen) getAltData(nt string, alt *ast.SyntaxAlternate, altI, altN int, isOrdered bool) *AltData {
// fmt.Printf("codex.getAltData %s[%d]\n", nt, altI)
L := gslot.NewLabel(nt, altI, 0, gslot.Unknown, g.gs, g.ff)
d := &AltData{
NT: nt,
AltLabel: L.Label(),
PassAltLabel: gslot.LabelFor(nt, altI, 0, gslot.Match),
AltComment: L.String(),
HasPass: altN > 1 && altI > 0,
}
if !alt.Empty() {
d.Slots = g.getSlotsData(nt, alt, altI, altN, isOrdered)
d.LastSlot = d.Slots[len(d.Slots)-1]
}
return d
}
func (g *gen) getSlotsData(nt string, alt *ast.SyntaxAlternate, altI, altN int, isOrdered bool) (data []*SlotData) {
resetTokens := false
for i, sym := range alt.Symbols {
// fmt.Printf("getSlotsData(%s) %s\n", nt, getSlotData(nt, altI, sym, i))
data = append(data, g.getSlotData(nt, altI, altN, sym.String(), i, len(alt.Symbols), &resetTokens, isOrdered))
}
return
}
func (g *gen) getSlotData(nt string, altI, altN int, symbol string, pos, maxPos int, resetTokens *bool, isOrdered bool) *SlotData {
preLabel := gslot.NewLabel(nt, altI, pos, gslot.Unknown, g.gs, g.ff)
postLabel := gslot.NewLabel(nt, altI, pos+1, gslot.Unknown, g.gs, g.ff)
var failLabel string
var passLabel string
if altI+1 < altN {
failLabel = `slot.` + gslot.LabelFor(nt, altI+1, 0, gslot.Unknown)
passLabel = `slot.` + gslot.LabelFor(nt, altI+1, 0, gslot.Match)
} else {
failLabel = `slot.` + gslot.LabelFor(nt, altN, 0, gslot.Fail)
passLabel = `failInd`
}
sd := &SlotData{
AltLabel: gslot.LabelFor(nt, altI, 0, gslot.Unknown),
PreLabel: preLabel.Label(),
PostLabel: postLabel.Label(),
FailLabel: failLabel,
PassLabel: passLabel,
PassPostLabel: gslot.LabelFor(nt, altI, pos, gslot.Match),
Comment: postLabel.String(),
NotLastAlt: altI+1 < altN,
IsNT: false,
IsPLook: false,
IsNLook: false,
Head: nt,
ResetTokens: *resetTokens,
NotLastSlot: pos+1 < maxPos,
}
if g.g.Terminals.Contain(symbol) {
sd.CallNT = "<error: not NT>"
*resetTokens = true // set up for subsequent iterations
} else if g.g.Lookaheads.Contain(symbol) {
switch symbol[0] {
case '&':
sd.IsPLook = true
case '!':
sd.IsNLook = true
default:
panic("Invalid lookahead symbol: " + symbol)
}
sd.CallNT = symbol[1:]
} else {
sd.IsNT = true
sd.CallNT = symbol
}
// fmt.Printf("getSlotData: altlabel:%s, pre:%s, post:%s\n",
// sd.AltLabel, sd.PreLabel, sd.PostLabel)
return sd
}
func (g *gen) getFailAlternate(nt string, nAlt int) string {
return ` case slot.` + gslot.LabelFor(nt, nAlt, 0, gslot.Fail) + `: // ` + nt + ` failure case
p.rtn(symbols.NT_` + nt + `, cU, failInd)
`
}
type SlotData struct {
AltLabel string
PreLabel string
PostLabel string
FailLabel string
PassLabel string
PassPostLabel string
Comment string
IsNT bool
IsPLook bool
IsNLook bool
CallNT string
NotLastAlt bool
Head string
ResetTokens bool
NotLastSlot bool
}
const eAltCodeTmpl = `case slot.{{.AltLabel}}: // {{.AltComment}}
p.bsrSet.AddEmpty(slot.{{.AltLabel}},p.cI)
p.rtn(symbols.NT_{{.NT}}, cU, p.cI)
`
const oAltCodeTmpl = ` case slot.{{.AltLabel}}: // {{.AltComment}}
{{range $i, $slot := .Slots}}
rext, ok = p.testSelect(slot.{{$slot.PreLabel}}, tokens)
if !ok {
p.parseError(slot.{{$slot.PreLabel}}, p.cI, tokens, first[slot.{{$slot.PreLabel}}])
L, p.cI = {{$slot.FailLabel}}, cU
{{if $slot.ResetTokens}}tokens = origTokens{{end}}
goto nextSlot
}
{{if $slot.IsNT}}p.call(slot.{{$slot.PostLabel}}, {{$slot.FailLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PostLabel}}: // {{$slot.Comment}}
{{else if $slot.IsPLook}}p.call(slot.{{$slot.PostLabel}}, {{$slot.FailLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PostLabel}}: // {{$slot.Comment}}
{{else if $slot.IsNLook}}p.call({{$slot.FailLabel}}, slot.{{$slot.PostLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PostLabel}}: // {{$slot.Comment}}
{{else}}p.bsrSet.Add(slot.{{$slot.PostLabel}}, cU, p.cI, rext)
p.cI = rext{{end}}{{end}}
p.rtn(symbols.NT_{{.NT}}, cU, p.cI)
`
const uAltCodeTmpl = ` case slot.{{.AltLabel}}: // {{.AltComment}}
{{range $i, $slot := .Slots}}
rext, ok = p.testSelect(slot.{{$slot.PreLabel}}, tokens)
if !ok {
p.parseError(slot.{{$slot.PreLabel}}, p.cI, tokens, first[slot.{{$slot.PreLabel}}])
L, p.cI = {{$slot.FailLabel}}, cU
{{if $slot.ResetTokens}}tokens = origTokens{{end}}
goto nextSlot
}
{{if $slot.IsNT}}p.call(slot.{{$slot.PostLabel}}, {{$slot.FailLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PostLabel}}: // {{$slot.Comment}}
{{else if $slot.IsPLook}}p.call(slot.{{$slot.PostLabel}}, {{$slot.FailLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PostLabel}}: // {{$slot.Comment}}
{{else if $slot.IsNLook}}p.call({{$slot.FailLabel}}, slot.{{$slot.PostLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PostLabel}}: // {{$slot.Comment}}
{{else}}p.bsrSet.Add(slot.{{$slot.PostLabel}}, cU, p.cI, rext)
p.cI = rext
{{if $slot.NotLastSlot}}tokens = p.lex.Tokens(p.cI){{end}}{{end}}
p.rtn(symbols.NT_{{$slot.Head}}, cU, p.cI)
{{if .NotLastAlt}}L, p.cI = {{$slot.PassLabel}}, cU
{{if $slot.ResetTokens}}tokens = origTokens{{end}}
goto nextSlot{{end}}{{end}}
{{if .HasPass}}case slot.{{.PassAltLabel}}: // {{.AltComment}} [with previous match]
{{range $i, $slot := .Slots}}
rext, ok = p.testSelect(slot.{{$slot.PreLabel}}, tokens)
if !ok {
p.parseError(slot.{{$slot.PreLabel}}, p.cI, tokens, first[slot.{{$slot.PreLabel}}])
{{if .NotLastAlt}}L, p.cI = {{$slot.PassLabel}}, cU
{{if $slot.ResetTokens}}tokens = origTokens{{end}}
goto nextSlot{{end}}
}
{{if $slot.IsNT}}p.call(slot.{{$slot.PassPostLabel}}, {{$slot.PassLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PassPostLabel}}: // {{$slot.Comment}}
{{else if $slot.IsPLook}}p.call(slot.{{$slot.PostLabel}}, {{$slot.PassLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PostLabel}}: // {{$slot.Comment}}
{{else if $slot.IsNLook}}p.call({{$slot.PassLabel}}, slot.{{$slot.PostLabel}}, symbols.NT_{{$slot.CallNT}}, cU, p.cI)
case slot.{{$slot.PostLabel}}: // {{$slot.Comment}}
{{else}}p.bsrSet.Add(slot.{{$slot.PostLabel}}, cU, p.cI, rext)
p.cI = rext
{{if $slot.NotLastSlot}}tokens = p.lex.Tokens(p.cI){{end}}{{end}}
p.rtn(symbols.NT_{{$slot.Head}}, cU, p.cI)
{{if .NotLastAlt}}L, p.cI = {{$slot.PassLabel}}, cU
{{if $slot.ResetTokens}}tokens = origTokens{{end}}
goto nextSlot{{end}}
{{end}}{{end}}
`