Add Chapter 9 code.

Chapter9/configurator/configurator.nim

@@ -0,0 +1,82 @@
+import macros
+
+proc createRefType(ident: NimIdent, identDefs: seq[NimNode]): NimNode =
+ result = newNimNode(nnkTypeSection).add(
+ newNimNode(nnkTypeDef).add(
+ newIdentNode(ident),
+ newEmptyNode(),
+ newNimNode(nnkRefTy).add(
+ newNimNode(nnkObjectTy).add(
+ newEmptyNode(),
+ newEmptyNode(),
+ newNimNode(nnkRecList).add(
+ identDefs
+ )
+ )
+ )
+ )
+ )
+
+proc toIdentDefs(stmtList: NimNode): seq[NimNode] =
+ expectKind(stmtList, nnkStmtList)
+ result = @[]
+
+ for child in stmtList:
+ expectKind(child, nnkCall)
+ result.add(newIdentDefs(child[0], child[1][0]))
+
+template constructor(ident: untyped): untyped =
+ proc `new ident`(): `ident` =
+ new result
+
+proc createLoadProc(typeName: NimIdent, identDefs: seq[NimNode]): NimNode =
+ var cfgIdent = newIdentNode("cfg")
+ var filenameIdent = newIdentNode("filename")
+ var objIdent = newIdentNode("obj")
+
+ var body = newStmtList()
+ body.add quote do:
+ var `objIdent` = parseFile(`filenameIdent`)
+
+ for identDef in identDefs:
+ let fieldNameIdent = identDef[0]
+ let fieldName = $fieldNameIdent.ident
+ case $identDef[1].ident
+ of "string":
+ body.add quote do:
+ `cfgIdent`.`fieldNameIdent` = `objIdent`[`fieldName`].getStr
+ of "int":
+ body.add quote do:
+ `cfgIdent`.`fieldNameIdent` = `objIdent`[`fieldName`].getNum().int
+ else:
+ doAssert(false, "Not Implemented")
+
+ return newProc(newIdentNode("load"),
+ [newEmptyNode(),
+ newIdentDefs(cfgIdent, newIdentNode(typeName)),
+ newIdentDefs(filenameIdent, newIdentNode("string"))],
+ body)
+
+macro config*(typeName: untyped, fields: untyped): untyped =
+ result = newStmtList()
+
+ let identDefs = toIdentDefs(fields)
+ result.add createRefType(typeName.ident, identDefs)
+ result.add getAst(constructor(typeName.ident))
+ result.add createLoadProc(typeName.ident, identDefs)
+
+ echo treeRepr(typeName)
+ echo treeRepr(fields)
+
+ echo treeRepr(result)
+ echo repr(result)
+
+import json
+config MyAppConfig:
+ address: string
+ echo(123)
+
+var myConf = newMyAppConfig()
+myConf.load("myappconfig.cfg")
+echo("Address: ", myConf.address)
+echo("Port: ", myConf.port)

Chapter9/configurator/myappconfig.cfg

@@ -0,0 +1,4 @@
+{
+ "address": "http:https://google.com",
+ "port": 80
+}