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discard """
output: '''
main started: a=10, b=inner-b, c=10, d=some-d, x=16, z=20
exiting: a=12, b=overridden-b, c=100, msg=bye bye, x=16
'''
"""
import macros, tables
template scopeHolder =
0 # scope revision number
type
BindingsSet = Table[string, NimNode]
proc actualBody(n: NimNode): NimNode =
# skip over the double StmtList node introduced in `mergeScopes`
result = n.body
if result.kind == nnkStmtList and result[0].kind == nnkStmtList:
result = result[0]
iterator bindings(n: NimNode, skip = 0): (string, NimNode) =
for i in skip ..< n.len:
let child = n[i]
if child.kind in {nnkAsgn, nnkExprEqExpr}:
let name = $child[0]
let value = child[1]
yield (name, value)
proc scopeRevision(scopeHolder: NimNode): int =
# get the revision number from a scopeHolder sym
assert scopeHolder.kind == nnkSym
var revisionNode = scopeHolder.getImpl.actualBody[0]
result = int(revisionNode.intVal)
proc lastScopeHolder(scopeHolders: NimNode): NimNode =
# get the most recent scopeHolder from a symChoice node
if scopeHolders.kind in {nnkClosedSymChoice, nnkOpenSymChoice}:
var bestScopeRev = 0
assert scopeHolders.len > 0
for scope in scopeHolders:
let rev = scope.scopeRevision
if result == nil or rev > bestScopeRev:
result = scope
bestScopeRev = rev
else:
result = scopeHolders
assert result.kind == nnkSym
macro mergeScopes(scopeHolders: typed, newBindings: untyped): untyped =
var
bestScope = scopeHolders.lastScopeHolder
bestScopeRev = bestScope.scopeRevision
var finalBindings = initTable[string, NimNode]()
for k, v in bindings(bestScope.getImpl.actualBody, skip = 1):
finalBindings[k] = v
for k, v in bindings(newBindings):
finalBindings[k] = v
var newScopeDefinition = newStmtList(newLit(bestScopeRev + 1))
for k, v in finalBindings:
newScopeDefinition.add newAssignment(newIdentNode(k), v)
result = quote:
template scopeHolder {.redefine.} = `newScopeDefinition`
template scope(newBindings: untyped) {.dirty.} =
mergeScopes(bindSym"scopeHolder", newBindings)
type
TextLogRecord = object
line: string
StdoutLogRecord = object
template setProperty(r: var TextLogRecord, key: string, val: string, isFirst: bool) =
if not first: r.line.add ", "
r.line.add key
r.line.add "="
r.line.add val
template setEventName(r: var StdoutLogRecord, name: string) =
stdout.write(name & ": ")
template setProperty(r: var StdoutLogRecord, key: string, val: auto, isFirst: bool) =
when not isFirst: stdout.write ", "
stdout.write key
stdout.write "="
stdout.write $val
template flushRecord(r: var StdoutLogRecord) =
stdout.write "\n"
stdout.flushFile
macro logImpl(scopeHolders: typed,
logStmtProps: varargs[untyped]): untyped =
let lexicalScope = scopeHolders.lastScopeHolder.getImpl.actualBody
var finalBindings = initOrderedTable[string, NimNode]()
for k, v in bindings(lexicalScope, skip = 1):
finalBindings[k] = v
for k, v in bindings(logStmtProps, skip = 1):
finalBindings[k] = v
finalBindings.sort(system.cmp)
let eventName = logStmtProps[0]
assert eventName.kind in {nnkStrLit}
let record = genSym(nskVar, "record")
result = quote:
var `record`: StdoutLogRecord
setEventName(`record`, `eventName`)
var isFirst = true
for k, v in finalBindings:
result.add newCall(newIdentNode"setProperty",
record, newLit(k), v, newLit(isFirst))
isFirst = false
result.add newCall(newIdentNode"flushRecord", record)
template log(props: varargs[untyped]) {.dirty.} =
logImpl(bindSym"scopeHolder", props)
scope:
a = 12
b = "original-b"
scope:
x = 16
b = "overridden-b"
scope:
c = 100
proc main =
scope:
c = 10
scope:
z = 20
log("main started", a = 10, b = "inner-b", d = "some-d")
main()
log("exiting", msg = "bye bye")
|
