github.com/slspeek/camlistore_namedsearch@v0.0.0-20140519202248-ed6f70f7721a/pkg/fs/time.go (about)

     1  // +build linux darwin
     2  
     3  /*
     4  Copyright 2013 Google Inc.
     5  
     6  Licensed under the Apache License, Version 2.0 (the "License");
     7  you may not use this file except in compliance with the License.
     8  You may obtain a copy of the License at
     9  
    10       http://www.apache.org/licenses/LICENSE-2.0
    11  
    12  Unless required by applicable law or agreed to in writing, software
    13  distributed under the License is distributed on an "AS IS" BASIS,
    14  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    15  See the License for the specific language governing permissions and
    16  limitations under the License.
    17  */
    18  
    19  package fs
    20  
    21  import (
    22  	"errors"
    23  	"fmt"
    24  	"math"
    25  	"strconv"
    26  	"time"
    27  )
    28  
    29  var timeFormats = []string{
    30  	time.RFC3339Nano,
    31  	time.RFC3339,
    32  	time.RFC1123Z,
    33  	time.RFC1123,
    34  	time.UnixDate,
    35  	time.ANSIC,
    36  	time.RubyDate,
    37  	"2006-01-02T15:04",
    38  	"2006-01-02T15",
    39  	"2006-01-02",
    40  	"2006-01",
    41  	"2006",
    42  }
    43  
    44  var errUnparseableTimestamp = errors.New("unparsable timestamp")
    45  
    46  var powTable = []int{
    47  	10e8,
    48  	10e7,
    49  	10e6,
    50  	10e5,
    51  	10e4,
    52  	10e3,
    53  	10e2,
    54  	10e1,
    55  	10,
    56  	1,
    57  }
    58  
    59  // Hand crafted this parser since it's a really common path.
    60  func parseCanonicalTime(in string) (time.Time, error) {
    61  	if len(in) < 20 || in[len(in)-1] != 'Z' {
    62  		return time.Time{}, errUnparseableTimestamp
    63  	}
    64  
    65  	if !(in[4] == '-' && in[7] == '-' && in[10] == 'T' &&
    66  		in[13] == ':' && in[16] == ':' && (in[19] == '.' || in[19] == 'Z')) {
    67  		return time.Time{}, fmt.Errorf("positionally incorrect: %v", in)
    68  	}
    69  
    70  	// 2012-08-28T21:24:35.37465188Z
    71  	//     4  7  10 13 16 19
    72  	// -----------------------------
    73  	// 0-4  5  8  11 14 17 20
    74  
    75  	year, err := strconv.Atoi(in[0:4])
    76  	if err != nil {
    77  		return time.Time{}, fmt.Errorf("error parsing year: %v", err)
    78  	}
    79  
    80  	month, err := strconv.Atoi(in[5:7])
    81  	if err != nil {
    82  		return time.Time{}, fmt.Errorf("error parsing month: %v", err)
    83  	}
    84  
    85  	day, err := strconv.Atoi(in[8:10])
    86  	if err != nil {
    87  		return time.Time{}, fmt.Errorf("error parsing day: %v", err)
    88  	}
    89  
    90  	hour, err := strconv.Atoi(in[11:13])
    91  	if err != nil {
    92  		return time.Time{}, fmt.Errorf("error parsing hour: %v", err)
    93  	}
    94  
    95  	minute, err := strconv.Atoi(in[14:16])
    96  	if err != nil {
    97  		return time.Time{}, fmt.Errorf("error parsing minute: %v", err)
    98  	}
    99  
   100  	second, err := strconv.Atoi(in[17:19])
   101  	if err != nil {
   102  		return time.Time{}, fmt.Errorf("error parsing second: %v", err)
   103  	}
   104  
   105  	var nsecstr string
   106  	if in[19] != 'Z' {
   107  		nsecstr = in[20 : len(in)-1]
   108  	}
   109  	var nsec int
   110  
   111  	if nsecstr != "" {
   112  		nsec, err = strconv.Atoi(nsecstr)
   113  		if err != nil {
   114  			return time.Time{}, fmt.Errorf("error parsing nanoseconds: %v", err)
   115  		}
   116  	}
   117  
   118  	nsec *= powTable[len(nsecstr)]
   119  
   120  	return time.Date(year, time.Month(month), day,
   121  		hour, minute, second, nsec, time.UTC), nil
   122  }
   123  
   124  func parseTime(in string) (time.Time, error) {
   125  	// First, try a few numerics
   126  	n, err := strconv.ParseInt(in, 10, 64)
   127  	if err == nil {
   128  		switch {
   129  		case n > int64(math.MaxInt32)*1000:
   130  			// nanosecond timestamps
   131  			return time.Unix(n/1e9, n%1e9), nil
   132  		case n > int64(math.MaxInt32):
   133  			// millisecond timestamps
   134  			return time.Unix(n/1000, (n%1000)*1e6), nil
   135  		case n > 10000:
   136  			// second timestamps
   137  			return time.Unix(n, 0), nil
   138  		}
   139  	}
   140  	rv, err := parseCanonicalTime(in)
   141  	if err == nil {
   142  		return rv, nil
   143  	}
   144  	for _, f := range timeFormats {
   145  		parsed, err := time.Parse(f, in)
   146  		if err == nil {
   147  			return parsed, nil
   148  		}
   149  	}
   150  	return time.Time{}, errUnparseableTimestamp
   151  }