Map support (#73)

* support maps with "key1:val1,key2:val2" syntax

* quote the invalid string in error msgs

* document map support in the README

closes #70

README.md

@@ -21,6 +21,7 @@ export MYAPP_USER=Kelsey
 export MYAPP_RATE="0.5"
 export MYAPP_TIMEOUT="3m"
 export MYAPP_USERS="rob,ken,robert"
+export MYAPP_COLORCODES="red:1,green:2,blue:3"
 ```
 
 Write some code:
@@ -37,12 +38,13 @@ import (
 )
 
 type Specification struct {
-    Debug   bool
-    Port    int
-    User    string
-    Users   []string
-    Rate    float32
-    Timeout time.Duration
+    Debug       bool
+    Port        int
+    User        string
+    Users       []string
+    Rate        float32
+    Timeout     time.Duration
+    ColorCodes  map[string]int
 }
 
 func main() {
@@ -61,6 +63,11 @@ func main() {
     for _, u := range s.Users {
         fmt.Printf("  %s\n", u)
     }
+
+    fmt.Println("Color codes:")
+    for k, v := range s.ColorCodes {
+        fmt.Printf("  %s: %d\n", k, v)
+    }
 }
 ```
 
@@ -76,6 +83,10 @@ Users:
   rob
   ken
   robert
+Color codes:
+  red: 1
+  green: 2
+  blue: 3
 ```
 
 ## Struct Tag Support
@@ -145,6 +156,8 @@ envconfig supports supports these struct field types:
   * int8, int16, int32, int64
   * bool
   * float32, float64
+  * slices of any supported type
+  * maps (keys and values of any supported type)
   * [encoding.TextUnmarshaler](https://golang.org/pkg/encoding/#TextUnmarshaler)
 
 Embedded structs using these fields are also supported.

envconfig.go

@@ -265,6 +265,27 @@ func processField(value string, field reflect.Value) error {
 			}
 		}
 		field.Set(sl)
+	case reflect.Map:
+		pairs := strings.Split(value, ",")
+		mp := reflect.MakeMap(typ)
+		for _, pair := range pairs {
+			kvpair := strings.Split(pair, ":")
+			if len(kvpair) != 2 {
+				return fmt.Errorf("invalid map item: %q", pair)
+			}
+			k := reflect.New(typ.Key()).Elem()
+			err := processField(kvpair[0], k)
+			if err != nil {
+				return err
+			}
+			v := reflect.New(typ.Elem()).Elem()
+			err = processField(kvpair[1], v)
+			if err != nil {
+				return err
+			}
+			mp.SetMapIndex(k, v)
+		}
+		field.Set(mp)
 	}
 
 	return nil

envconfig_test.go

@@ -32,6 +32,7 @@ type Specification struct {
 	Timeout                      time.Duration
 	AdminUsers                   []string
 	MagicNumbers                 []int
+	ColorCodes                   map[string]int
 	MultiWordVar                 string
 	MultiWordVarWithAutoSplit    uint32 `split_words:"true"`
 	SomePointer                  *string
@@ -77,6 +78,7 @@ func TestProcess(t *testing.T) {
 	os.Setenv("ENV_CONFIG_TIMEOUT", "2m")
 	os.Setenv("ENV_CONFIG_ADMINUSERS", "John,Adam,Will")
 	os.Setenv("ENV_CONFIG_MAGICNUMBERS", "5,10,20")
+	os.Setenv("ENV_CONFIG_COLORCODES", "red:1,green:2,blue:3")
 	os.Setenv("SERVICE_HOST", "127.0.0.1")
 	os.Setenv("ENV_CONFIG_TTL", "30")
 	os.Setenv("ENV_CONFIG_REQUIREDVAR", "foo")
@@ -130,6 +132,21 @@ func TestProcess(t *testing.T) {
 		t.Errorf("expected empty string, got %#v", s.Ignored)
 	}
 
+	if len(s.ColorCodes) != 3 ||
+		s.ColorCodes["red"] != 1 ||
+		s.ColorCodes["green"] != 2 ||
+		s.ColorCodes["blue"] != 3 {
+		t.Errorf(
+			"expected %#v, got %#v",
+			map[string]int{
+				"red":   1,
+				"green": 2,
+				"blue":  3,
+			},
+			s.ColorCodes,
+		)
+	}
+
 	if s.NestedSpecification.Property != "iamnested" {
 		t.Errorf("expected '%s' string, got %#v", "iamnested", s.NestedSpecification.Property)
 	}

testdata/custom.txt

@@ -11,6 +11,7 @@ ENV_CONFIG_TTL=
 ENV_CONFIG_TIMEOUT=
 ENV_CONFIG_ADMINUSERS=
 ENV_CONFIG_MAGICNUMBERS=
+ENV_CONFIG_COLORCODES=
 ENV_CONFIG_MULTIWORDVAR=
 ENV_CONFIG_MULTI_WORD_VAR_WITH_AUTO_SPLIT=
 ENV_CONFIG_SOMEPOINTER=

testdata/default_list.txt

@@ -66,6 +66,11 @@ ENV_CONFIG_MAGICNUMBERS
 ..[type]........Comma-separated.list.of.Integer
 ..[default].....
 ..[required]....
+ENV_CONFIG_COLORCODES
+..[description].
+..[type]........Comma-separated.list.of.String:Integer.pairs
+..[default].....
+..[required]....
 ENV_CONFIG_MULTIWORDVAR
 ..[description].
 ..[type]........String

testdata/default_table.txt

@@ -1,33 +1,34 @@
 This.application.is.configured.via.the.environment..The.following.environment
 variables.can.be.used:
 
-KEY..............................................TYPE...............................DEFAULT...........REQUIRED....DESCRIPTION
-ENV_CONFIG_ENABLED...............................True.or.False....................................................some.embedded.value
-ENV_CONFIG_EMBEDDEDPORT..........................Integer..........................................................
-ENV_CONFIG_MULTIWORDVAR..........................String...........................................................
-ENV_CONFIG_MULTI_WITH_DIFFERENT_ALT..............String...........................................................
-ENV_CONFIG_EMBEDDED_WITH_ALT.....................String...........................................................
-ENV_CONFIG_DEBUG.................................True.or.False....................................................
-ENV_CONFIG_PORT..................................Integer..........................................................
-ENV_CONFIG_RATE..................................Float............................................................
-ENV_CONFIG_USER..................................String...........................................................
-ENV_CONFIG_TTL...................................Unsigned.Integer.................................................
-ENV_CONFIG_TIMEOUT...............................Duration.........................................................
-ENV_CONFIG_ADMINUSERS............................Comma-separated.list.of.String...................................
-ENV_CONFIG_MAGICNUMBERS..........................Comma-separated.list.of.Integer..................................
-ENV_CONFIG_MULTIWORDVAR..........................String...........................................................
-ENV_CONFIG_MULTI_WORD_VAR_WITH_AUTO_SPLIT........Unsigned.Integer.................................................
-ENV_CONFIG_SOMEPOINTER...........................String...........................................................
-ENV_CONFIG_SOMEPOINTERWITHDEFAULT................String.............................foo2baz.......................foorbar.is.the.word
-ENV_CONFIG_MULTI_WORD_VAR_WITH_ALT...............String...........................................................what.alt
-ENV_CONFIG_MULTI_WORD_VAR_WITH_LOWER_CASE_ALT....String...........................................................
-ENV_CONFIG_SERVICE_HOST..........................String...........................................................
-ENV_CONFIG_DEFAULTVAR............................String.............................foobar........................
-ENV_CONFIG_REQUIREDVAR...........................String...............................................true........
-ENV_CONFIG_BROKER................................String.............................127.0.0.1.....................
-ENV_CONFIG_REQUIREDDEFAULT.......................String.............................foo2bar...........true........
-ENV_CONFIG_OUTER_INNER...........................String...........................................................
-ENV_CONFIG_OUTER_PROPERTYWITHDEFAULT.............String.............................fuzzybydefault................
-ENV_CONFIG_AFTERNESTED...........................String...........................................................
-ENV_CONFIG_HONOR.................................HonorDecodeInStruct..............................................
-ENV_CONFIG_DATETIME..............................Time.............................................................
+KEY..............................................TYPE............................................DEFAULT...........REQUIRED....DESCRIPTION
+ENV_CONFIG_ENABLED...............................True.or.False.................................................................some.embedded.value
+ENV_CONFIG_EMBEDDEDPORT..........................Integer.......................................................................
+ENV_CONFIG_MULTIWORDVAR..........................String........................................................................
+ENV_CONFIG_MULTI_WITH_DIFFERENT_ALT..............String........................................................................
+ENV_CONFIG_EMBEDDED_WITH_ALT.....................String........................................................................
+ENV_CONFIG_DEBUG.................................True.or.False.................................................................
+ENV_CONFIG_PORT..................................Integer.......................................................................
+ENV_CONFIG_RATE..................................Float.........................................................................
+ENV_CONFIG_USER..................................String........................................................................
+ENV_CONFIG_TTL...................................Unsigned.Integer..............................................................
+ENV_CONFIG_TIMEOUT...............................Duration......................................................................
+ENV_CONFIG_ADMINUSERS............................Comma-separated.list.of.String................................................
+ENV_CONFIG_MAGICNUMBERS..........................Comma-separated.list.of.Integer...............................................
+ENV_CONFIG_COLORCODES............................Comma-separated.list.of.String:Integer.pairs..................................
+ENV_CONFIG_MULTIWORDVAR..........................String........................................................................
+ENV_CONFIG_MULTI_WORD_VAR_WITH_AUTO_SPLIT........Unsigned.Integer..............................................................
+ENV_CONFIG_SOMEPOINTER...........................String........................................................................
+ENV_CONFIG_SOMEPOINTERWITHDEFAULT................String..........................................foo2baz.......................foorbar.is.the.word
+ENV_CONFIG_MULTI_WORD_VAR_WITH_ALT...............String........................................................................what.alt
+ENV_CONFIG_MULTI_WORD_VAR_WITH_LOWER_CASE_ALT....String........................................................................
+ENV_CONFIG_SERVICE_HOST..........................String........................................................................
+ENV_CONFIG_DEFAULTVAR............................String..........................................foobar........................
+ENV_CONFIG_REQUIREDVAR...........................String............................................................true........
+ENV_CONFIG_BROKER................................String..........................................127.0.0.1.....................
+ENV_CONFIG_REQUIREDDEFAULT.......................String..........................................foo2bar...........true........
+ENV_CONFIG_OUTER_INNER...........................String........................................................................
+ENV_CONFIG_OUTER_PROPERTYWITHDEFAULT.............String..........................................fuzzybydefault................
+ENV_CONFIG_AFTERNESTED...........................String........................................................................
+ENV_CONFIG_HONOR.................................HonorDecodeInStruct...........................................................
+ENV_CONFIG_DATETIME..............................Time..........................................................................

testdata/fault.txt

@@ -27,3 +27,4 @@
 {.Key}
 {.Key}
 {.Key}
+{.Key}

usage.go

@@ -56,6 +56,12 @@ func toTypeDescription(t reflect.Type) string {
 	switch t.Kind() {
 	case reflect.Array, reflect.Slice:
 		return fmt.Sprintf("Comma-separated list of %s", toTypeDescription(t.Elem()))
+	case reflect.Map:
+		return fmt.Sprintf(
+			"Comma-separated list of %s:%s pairs",
+			toTypeDescription(t.Key()),
+			toTypeDescription(t.Elem()),
+		)
 	case reflect.Ptr:
 		return toTypeDescription(t.Elem())
 	case reflect.Struct: