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84 lines
2.5 KiB
Nim
84 lines
2.5 KiB
Nim
#
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#
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# The Nimrod Compiler
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# (c) Copyright 2012 Andreas Rumpf
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#
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# See the file "copying.txt", included in this
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# distribution, for details about the copyright.
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#
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## Template evaluation engine. Now hygienic.
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import
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strutils, options, ast, astalgo, msgs, os, idents, wordrecg, renderer,
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rodread
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type
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TemplCtx {.pure, final.} = object
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owner, genSymOwner: PSym
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mapping: TIdTable # every gensym'ed symbol needs to be mapped to some
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# new symbol
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proc evalTemplateAux(templ, actual: PNode, c: var TemplCtx): PNode =
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#inc genSymBaseId
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case templ.kind
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of nkSym:
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var s = templ.sym
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if s.owner.id == c.owner.id:
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if s.kind == skParam:
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result = copyTree(actual.sons[s.position])
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else:
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InternalAssert sfGenSym in s.flags
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var x = PSym(IdTableGet(c.mapping, s))
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if x == nil:
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x = copySym(s, false)
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x.owner = c.genSymOwner
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IdTablePut(c.mapping, s, x)
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result = newSymNode(x, templ.info)
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else:
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result = copyNode(templ)
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of nkNone..nkIdent, nkType..nkNilLit: # atom
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result = copyNode(templ)
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else:
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result = copyNode(templ)
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newSons(result, sonsLen(templ))
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for i in countup(0, sonsLen(templ) - 1):
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result.sons[i] = evalTemplateAux(templ.sons[i], actual, c)
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proc evalTemplateArgs(n: PNode, s: PSym): PNode =
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# if the template has zero arguments, it can be called without ``()``
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# `n` is then a nkSym or something similar
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var a: int
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case n.kind
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of nkCall, nkInfix, nkPrefix, nkPostfix, nkCommand, nkCallStrLit:
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a = sonsLen(n)
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else: a = 0
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var f = s.typ.sonsLen
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if a > f: GlobalError(n.info, errWrongNumberOfArguments)
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result = copyNode(n)
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for i in countup(1, f - 1):
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var arg = if i < a: n.sons[i] else: copyTree(s.typ.n.sons[i].sym.ast)
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if arg == nil or arg.kind == nkEmpty:
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LocalError(n.info, errWrongNumberOfArguments)
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addSon(result, arg)
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var evalTemplateCounter* = 0
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# to prevent endless recursion in templates instantiation
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proc evalTemplate*(n: PNode, tmpl, genSymOwner: PSym): PNode =
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inc(evalTemplateCounter)
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if evalTemplateCounter > 100:
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GlobalError(n.info, errTemplateInstantiationTooNested)
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result = n
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# replace each param by the corresponding node:
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var args = evalTemplateArgs(n, tmpl)
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var ctx: TemplCtx
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ctx.owner = tmpl
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ctx.genSymOwner = genSymOwner
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initIdTable(ctx.mapping)
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result = evalTemplateAux(tmpl.getBody, args, ctx)
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dec(evalTemplateCounter)
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