github.com/nalum/terraform@v0.3.2-0.20141223102918-aa2c22ffeff6/flatmap/expand.go (about)

     1  package flatmap
     2  
     3  import (
     4  	"fmt"
     5  	"strconv"
     6  	"strings"
     7  )
     8  
     9  // Expand takes a map and a key (prefix) and expands that value into
    10  // a more complex structure. This is the reverse of the Flatten operation.
    11  func Expand(m map[string]string, key string) interface{} {
    12  	// If the key is exactly a key in the map, just return it
    13  	if v, ok := m[key]; ok {
    14  		if v == "true" {
    15  			return true
    16  		} else if v == "false" {
    17  			return false
    18  		}
    19  
    20  		return v
    21  	}
    22  
    23  	// Check if the key is an array, and if so, expand the array
    24  	if _, ok := m[key+".#"]; ok {
    25  		return expandArray(m, key)
    26  	}
    27  
    28  	// Check if this is a prefix in the map
    29  	prefix := key + "."
    30  	for k, _ := range m {
    31  		if strings.HasPrefix(k, prefix) {
    32  			return expandMap(m, prefix)
    33  		}
    34  	}
    35  
    36  	return nil
    37  }
    38  
    39  func expandArray(m map[string]string, prefix string) []interface{} {
    40  	num, err := strconv.ParseInt(m[prefix+".#"], 0, 0)
    41  	if err != nil {
    42  		panic(err)
    43  	}
    44  
    45  	result := make([]interface{}, num)
    46  	for i := 0; i < int(num); i++ {
    47  		result[i] = Expand(m, fmt.Sprintf("%s.%d", prefix, i))
    48  	}
    49  
    50  	return result
    51  }
    52  
    53  func expandMap(m map[string]string, prefix string) map[string]interface{} {
    54  	result := make(map[string]interface{})
    55  	for k, _ := range m {
    56  		if !strings.HasPrefix(k, prefix) {
    57  			continue
    58  		}
    59  
    60  		key := k[len(prefix):]
    61  		idx := strings.Index(key, ".")
    62  		if idx != -1 {
    63  			key = key[:idx]
    64  		}
    65  		if _, ok := result[key]; ok {
    66  			continue
    67  		}
    68  
    69  		// It contains a period, so it is a more complex structure
    70  		result[key] = Expand(m, k[:len(prefix)+len(key)])
    71  	}
    72  
    73  	return result
    74  }