github.com/joshdk/godel@v0.0.0-20170529232908-862138a45aee/properties/reader.go (about)

     1  // Copyright 2016 Palantir Technologies, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package properties
    16  
    17  import (
    18  	"fmt"
    19  	"io/ioutil"
    20  	"strings"
    21  )
    22  
    23  const URL = "distributionURL"
    24  const Checksum = "distributionSHA256"
    25  
    26  // Read reads the file at the provided path and returns a map of the properties that it contains. The file should
    27  // contain one property per line and the line should be of the form "key=value". Any line that starts with the character
    28  // '#' is ignored.
    29  func Read(path string) (map[string]string, error) {
    30  	bytes, err := ioutil.ReadFile(path)
    31  	if err != nil {
    32  		return nil, fmt.Errorf("Failed to read file %v: %v", path, err)
    33  	}
    34  
    35  	properties := make(map[string]string)
    36  
    37  	lines := strings.Split(string(bytes), "\n")
    38  	for _, currLine := range lines {
    39  		currLine = strings.TrimSpace(currLine)
    40  
    41  		if strings.HasPrefix(currLine, "#") || len(currLine) == 0 {
    42  			continue
    43  		}
    44  
    45  		equalsIndex := strings.IndexAny(currLine, "=")
    46  		if equalsIndex == -1 {
    47  			return nil, fmt.Errorf(`Failed to find character "=" in line "%v" in file with lines "%v"`, currLine, lines)
    48  		}
    49  
    50  		properties[currLine[:equalsIndex]] = currLine[equalsIndex+1:]
    51  	}
    52  	return properties, nil
    53  }
    54  
    55  // Get returns the specified property from the provided map or returns an error if the requested key does not exist
    56  // in the provided map.
    57  func Get(properties map[string]string, key string) (string, error) {
    58  	if value, ok := properties[key]; ok {
    59  		return value, nil
    60  	}
    61  	return "", fmt.Errorf("property %v did not exist in map %v", key, properties)
    62  }