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#
#
# The Nim Compiler
# (c) Copyright 2013 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## Template evaluation engine. Now hygienic.
import options, ast, astalgo, msgs, renderer, lineinfos, idents, trees
import std/strutils
type
TemplCtx = object
owner, genSymOwner: PSym
instLines: bool # use the instantiation lines numbers
isDeclarative: bool
mapping: SymMapping # every gensym'ed symbol needs to be mapped to some
# new symbol
config: ConfigRef
ic: IdentCache
instID: int
idgen: IdGenerator
proc copyNode(ctx: TemplCtx, a, b: PNode): PNode =
result = copyNode(a)
if ctx.instLines: setInfoRecursive(result, b.info)
proc evalTemplateAux(templ, actual: PNode, c: var TemplCtx, result: PNode) =
template handleParam(param) =
let x = param
if x.kind == nkArgList:
for y in items(x): result.add(y)
elif nfDefaultRefsParam in x.flags:
# value of default param needs to be evaluated like template body
# if it contains other template params
var res: PNode
if isAtom(x):
res = newNodeI(nkPar, x.info)
evalTemplateAux(x, actual, c, res)
if res.len == 1: res = res[0]
else:
res = copyNode(x)
for i in 0..<x.safeLen:
evalTemplateAux(x[i], actual, c, res)
result.add res
else:
result.add copyTree(x)
case templ.kind
of nkSym:
var s = templ.sym
if (s.owner == nil and s.kind == skParam) or s.owner == c.owner:
if s.kind == skParam and {sfGenSym, sfTemplateParam} * s.flags == {sfTemplateParam}:
handleParam actual[s.position]
elif (s.owner != nil) and (s.kind == skGenericParam or
s.kind == skType and s.typ != nil and s.typ.kind == tyGenericParam):
handleParam actual[s.owner.typ.signatureLen + s.position - 1]
else:
internalAssert c.config, sfGenSym in s.flags or s.kind == skType
var x = idTableGet(c.mapping, s)
if x == nil:
x = copySym(s, c.idgen)
# sem'check needs to set the owner properly later, see bug #9476
x.owner = nil # c.genSymOwner
#if x.kind == skParam and x.owner.kind == skModule:
# internalAssert c.config, false
idTablePut(c.mapping, s, x)
if sfGenSym in s.flags:
# TODO: getIdent(c.ic, "`" & x.name.s & "`gensym" & $c.instID)
result.add newIdentNode(getIdent(c.ic, x.name.s & "`gensym" & $c.instID),
if c.instLines: actual.info else: templ.info)
else:
result.add newSymNode(x, if c.instLines: actual.info else: templ.info)
else:
result.add copyNode(c, templ, actual)
of nkNone..nkIdent, nkType..nkNilLit: # atom
result.add copyNode(c, templ, actual)
of nkCommentStmt:
# for the documentation generator we don't keep documentation comments
# in the AST that would confuse it (bug #9432), but only if we are not in a
# "declarative" context (bug #9235).
if c.isDeclarative:
var res = copyNode(c, templ, actual)
for i in 0..<templ.len:
evalTemplateAux(templ[i], actual, c, res)
result.add res
else:
result.add newNodeI(nkEmpty, templ.info)
else:
var isDeclarative = false
if templ.kind in {nkProcDef, nkFuncDef, nkMethodDef, nkIteratorDef,
nkMacroDef, nkTemplateDef, nkConverterDef, nkTypeSection,
nkVarSection, nkLetSection, nkConstSection} and
not c.isDeclarative:
c.isDeclarative = true
isDeclarative = true
if (not c.isDeclarative) and templ.kind in nkCallKinds and isRunnableExamples(templ[0]):
# fixes bug #16993, bug #18054
discard
else:
var res = copyNode(c, templ, actual)
for i in 0..<templ.len:
evalTemplateAux(templ[i], actual, c, res)
result.add res
if isDeclarative: c.isDeclarative = false
const
errWrongNumberOfArguments = "wrong number of arguments"
errMissingGenericParamsForTemplate = "'$1' has unspecified generic parameters"
errTemplateInstantiationTooNested = "template instantiation too nested"
proc evalTemplateArgs(n: PNode, s: PSym; conf: ConfigRef; fromHlo: bool): PNode =
# if the template has zero arguments, it can be called without ``()``
# `n` is then a nkSym or something similar
var totalParams = case n.kind
of nkCallKinds: n.len-1
else: 0
var
# XXX: Since immediate templates are not subject to the
# standard sigmatching algorithm, they will have a number
# of deficiencies when it comes to generic params:
# Type dependencies between the parameters won't be honoured
# and the bound generic symbols won't be resolvable within
# their bodies. We could try to fix this, but it may be
# wiser to just deprecate immediate templates and macros
# now that we have working untyped parameters.
genericParams = if fromHlo: 0
else: s.ast[genericParamsPos].len
expectedRegularParams = s.typ.paramsLen
givenRegularParams = totalParams - genericParams
if givenRegularParams < 0: givenRegularParams = 0
if totalParams > expectedRegularParams + genericParams:
globalError(conf, n.info, errWrongNumberOfArguments)
if totalParams < genericParams:
globalError(conf, n.info, errMissingGenericParamsForTemplate %
n.renderTree)
result = newNodeI(nkArgList, n.info)
for i in 1..givenRegularParams:
result.add n[i]
# handle parameters with default values, which were
# not supplied by the user
for i in givenRegularParams+1..expectedRegularParams:
let default = s.typ.n[i].sym.ast
if default.isNil or default.kind == nkEmpty:
localError(conf, n.info, errWrongNumberOfArguments)
result.add newNodeI(nkEmpty, n.info)
else:
result.add default.copyTree
# add any generic parameters
for i in 1..genericParams:
result.add n[givenRegularParams + i]
# to prevent endless recursion in template instantiation
const evalTemplateLimit* = 1000
proc wrapInComesFrom*(info: TLineInfo; sym: PSym; res: PNode): PNode =
when true:
result = res
result.info = info
if result.kind in {nkStmtList, nkStmtListExpr} and result.len > 0:
result.lastSon.info = info
when false:
# this hack is required to
var x = result
while x.kind == nkStmtListExpr: x = x.lastSon
if x.kind in nkCallKinds:
for i in 1..<x.len:
if x[i].kind in nkCallKinds:
x[i].info = info
else:
result = newNodeI(nkStmtListExpr, info)
var d = newNodeI(nkComesFrom, info)
d.add newSymNode(sym, info)
result.add d
result.add res
result.typ = res.typ
proc evalTemplate*(n: PNode, tmpl, genSymOwner: PSym;
conf: ConfigRef;
ic: IdentCache; instID: ref int;
idgen: IdGenerator;
fromHlo=false): PNode =
inc(conf.evalTemplateCounter)
if conf.evalTemplateCounter > evalTemplateLimit:
globalError(conf, n.info, errTemplateInstantiationTooNested)
result = n
# replace each param by the corresponding node:
var args = evalTemplateArgs(n, tmpl, conf, fromHlo)
var ctx = TemplCtx(owner: tmpl,
genSymOwner: genSymOwner,
config: conf,
ic: ic,
mapping: initSymMapping(),
instID: instID[],
idgen: idgen
)
let body = tmpl.ast[bodyPos]
#echo "instantion of ", renderTree(body, {renderIds})
if isAtom(body):
result = newNodeI(nkPar, body.info)
evalTemplateAux(body, args, ctx, result)
if result.len == 1: result = result[0]
else:
localError(conf, result.info, "illformed AST: " &
renderTree(result, {renderNoComments}))
else:
result = copyNode(body)
ctx.instLines = sfCallsite in tmpl.flags
if ctx.instLines:
setInfoRecursive(result, n.info)
for i in 0..<body.safeLen:
evalTemplateAux(body[i], args, ctx, result)
result.flags.incl nfFromTemplate
result = wrapInComesFrom(n.info, tmpl, result)
#if ctx.debugActive:
# echo "instantion of ", renderTree(result, {renderIds})
dec(conf.evalTemplateCounter)
# The instID must be unique for every template instantiation, so we increment it here
inc instID[]
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