71 lines
1.8 KiB
Go
71 lines
1.8 KiB
Go
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/* SHS: Syntactically Homogeneous Shell
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* Copyright (C) 2019 Aidan Hahn
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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package ast
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type Tree *Token
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func (Tree t) Eval(FuncTable funcs, VarTable vars) Tree {
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if t == nil {
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return
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}
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var iter *Token
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eligibleForSystemCall := true
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reduce := func(Tree t_) Tree {
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if t_.Next != nil {
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t_.Next = reduce(t_.Next)
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}
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switch (t_.Tag) {
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case SYMBOL:
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maybeToken := GetVar(t_.Inner, vars)
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if maybeToken != nil {
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tok := maybeToken.Eval(funcs, vars)
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if tok == LIST {
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eligibleForSystemCall = false
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}
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}
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case LIST:
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eligibleForSystemCall = false
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t.Inner = Eval(t_.Inner)
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}
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return t_
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}
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ret := reduce(t)
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if ret.Tag == SYMBOL {
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f := funcs.GetFunction(ret.Inner)
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if f == nil {
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if !eligibleForSystemCall {
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// TODO: log error
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return nil
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}
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// hook into stdlib exec
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return
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}
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return (*f).CallFunction(ret.Next)
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}
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return ret
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}
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