mnpkg/scope.nim
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import
strutils,
critbits
import
parser
proc copy*(s: ref MnScope): ref MnScope =
var scope = newScope(s.parent)
scope.symbols = s.symbols
new(result)
result[] = scope
proc getSymbol*(scope: ref MnScope, key: string, acc=0): MnOperator =
if scope.symbols.hasKey(key):
return scope.symbols[key]
else:
if scope.parent.isNil:
raiseUndefined("Symbol '$1' not found." % key)
return scope.parent.getSymbol(key, acc + 1)
proc hasSymbol*(scope: ref MnScope, key: string): bool =
if scope.isNil:
return false
elif scope.symbols.hasKey(key):
return true
elif not scope.parent.isNil:
return scope.parent.hasSymbol(key)
else:
return false
proc delSymbol*(scope: ref MnScope, key: string): bool {.discardable.}=
if scope.symbols.hasKey(key):
if scope.symbols[key].sealed:
raiseInvalid("Symbol '$1' is sealed." % key)
scope.symbols.excl(key)
return true
return false
proc setSymbol*(scope: ref MnScope, key: string, value: MnOperator, override = false): bool {.discardable.}=
result = false
# check if a symbol already exists in current scope
if not scope.isNil and scope.symbols.hasKey(key):
if not override and scope.symbols[key].sealed:
raiseInvalid("Symbol '$1' is sealed ." % key)
scope.symbols[key] = value
result = true
else:
# Go up the scope chain and attempt to find the symbol
if not scope.parent.isNil:
result = scope.parent.setSymbol(key, value, override)
proc previous*(scope: ref MnScope): ref MnScope =
if scope.parent.isNil:
return scope
else:
return scope.parent
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