Add the ability to query for config values from specific sources.

cliutils.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version       = "0.12.0"
+version       = "0.12.1"
 author        = "Jonathan Bernard"
 description   = "Helper functions for writing command line interfaces."
 license       = "MIT"

cliutils/config.nim

@@ -1,4 +1,4 @@
-import std/[json, os, sequtils, strtabs, strutils]
+import std/[json, options, os, sequtils, strtabs, strutils]
 import docopt, identcasing, regex
 
 type
@@ -100,6 +100,17 @@ proc findConfigFile*(name: string, otherLocations: seq[string] = @[]): string =
     raise newException(ValueError, "could not find configuration file")
 
 
+proc jsonConfigNodeToString(node: JsonNode): string =
+  case node.kind
+  of JString: node.getStr
+  of JInt: $node.getInt
+  of JFloat: $node.getFloat
+  of JBool: $node.getBool
+  of JNull: ""
+  of JObject: $node
+  of JArray: $node
+
+
 proc getValueAndProvenance*(
     cfg: CombinedConfig,
     key: string): tuple[value: string, provenance: ValueProvenance]
@@ -111,17 +122,7 @@ proc getValueAndProvenance*(
   elif existsEnv(envKey):
     return (getEnv(envKey), ValueProvenance.environment)
   elif cfg.json.hasKey(jsonKey):
-    let node = cfg.json[jsonKey]
-    let value =
-      case node.kind
-      of JString: node.getStr
-      of JInt: $node.getInt
-      of JFloat: $node.getFloat
-      of JBool: $node.getBool
-      of JNull: ""
-      of JObject: $node
-      of JArray: $node
-    return (value, ValueProvenance.json)
+    return (jsonConfigNodeToString(cfg.json[jsonKey]), ValueProvenance.json)
   else: raise newException(ValueError, "cannot find a configuration value for \"" & key & "\"")
 
 
@@ -146,6 +147,22 @@ proc getVal*(cfg: CombinedConfig, key, default: string): string {.raises: [].} =
 proc `[]`*(cfg: CombinedConfig, key: string): string = getVal(cfg, key)
 
 
+proc getValueFromSource*(
+    cfg: CombinedConfig,
+    source: ValueProvenance,
+    key: string): Option[string] =
+
+  result = none[string]()
+  let (argKey, envKey, jsonKey) = keyNames(key)
+  if source == ValueProvenance.arguments and
+     cfg.docopt.contains(argKey) and cfg.docopt[argKey]:
+    result = some($cfg.docopt[argKey])
+  elif source == ValueProvenance.environment and existsEnv(envKey):
+    result = some(getEnv(envKey))
+  elif source == ValueProvenance.json and cfg.json.hasKey(jsonKey):
+    result = some(jsonConfigNodeToString(cfg.json[jsonKey]))
+
+
 proc getJsonValueAndProvenance*(
     cfg: CombinedConfig,
     key: string): tuple[value: JsonNode, provenance: ValueProvenance]
@@ -191,6 +208,22 @@ proc getJson*(
   except CatchableError: return default
 
 
+proc getJsonFromSource*(
+    cfg: CombinedConfig,
+    source: ValueProvenance,
+    key: string): Option[JsonNode] =
+
+  result = none[JsonNode]()
+  let (argKey, envKey, jsonKey) = keyNames(key)
+  if source == ValueProvenance.arguments and
+     cfg.docopt.contains(argKey) and cfg.docopt[argKey]:
+    result = some(parseJson($cfg.docopt[argKey]))
+  elif source == ValueProvenance.environment and existsEnv(envKey):
+    result = some(parseJson(getEnv(envKey)))
+  elif source == ValueProvenance.json and cfg.json.hasKey(jsonKey):
+    result = some(cfg.json[jsonKey])
+
+
 proc hasKey*(cfg: CombinedConfig, key: string): bool =
   let (argKey, envKey, jsonKey) = keyNames(key)