client-libraries/scala/src/main/scala/com/redis/Operations/ListOperations.scala

   1 package com.redis.operations
   2
   3 /**
   4  * Redis list operations
   5  *
   6  */
   7
   8 trait ListOperations{
   9
  10   def getConnection(key: String): Connection
  11
  12   // add the string value to the head (LPUSH) or tail (RPUSH) of the list stored at key.
  13   // If the key does not exist an empty list is created just before the append operation. If the key exists but is not a List an error is returned.
  14   // LPUSH
  15   def pushHead(key: String, value: String): Boolean = {
  16     val connection = getConnection(key)
  17     connection.write("LPUSH "+key+" "+value.length+"\r\n"+value+"\r\n")
  18     connection.readBoolean
  19   }
  20
  21   // RPUSH
  22   def pushTail(key: String, value: String): Boolean = {
  23     val connection = getConnection(key)
  24     connection.write("RPUSH "+key+" "+value.length+"\r\n"+value+"\r\n")
  25     connection.readBoolean
  26   }
  27
  28   // LPOP
  29   // atomically return and remove the first (LPOP) or last (RPOP) element of the list
  30   def popHead(key: String): String = {
  31     val connection = getConnection(key)
  32     connection.write("LPOP "+key+"\r\n")
  33     connection.readString
  34   }
  35
  36   // RPOP
  37   // atomically return and remove the first (LPOP) or last (RPOP) element of the list
  38   def popTail(key: String): String = {
  39     val connection = getConnection(key)
  40     connection.write("RPOP "+key+"\r\n")
  41     connection.readString
  42   }
  43
  44   // LINDEX
  45   // return the especified element of the list stored at the specified key. 0 is the first element, 1 the second and so on.
  46   // Negative indexes are supported, for example -1 is the last element, -2 the penultimate and so on.
  47   def listIndex(key: String, index: Int): String = {
  48     val connection = getConnection(key)
  49     connection.write("LINDEX "+key+" "+index+"\r\n")
  50     connection.readString
  51   }
  52
  53   // LSET
  54   // set the list element at index with the new value. Out of range indexes will generate an error
  55   def listSet(key: String, index: Int, value: String): Boolean = {
  56     val connection = getConnection(key)
  57     connection.write("LSET "+key+" "+index+" "+value.length+"\r\n"+value+"\r\n")
  58     connection.readBoolean
  59   }
  60
  61   // LLEN
  62   // return the length of the list stored at the specified key.
  63   // If the key does not exist zero is returned (the same behaviour as for empty lists). If the value stored at key is not a list an error is returned.
  64   def listLength(key: String): Int = {
  65     val connection = getConnection(key)
  66     connection.write("LLEN "+key+"\r\n")
  67     connection.readInt
  68   }
  69
  70   // LRANGE
  71   // return the specified elements of the list stored at the specified key.
  72   // Start and end are zero-based indexes. 0 is the first element of the list (the list head), 1 the next element and so on.
  73   def listRange(key: String, start: Int, end: Int): List[String] = {
  74     val connection = getConnection(key)
  75     connection.write("LRANGE "+key+" "+start+" "+end+"\r\n")
  76     connection.readList
  77   }
  78
  79   // LTRIM
  80   // Trim an existing list so that it will contain only the specified range of elements specified.
  81   def listTrim(key: String, start: Int, end: Int): Boolean = {
  82     val connection = getConnection(key)
  83     connection.write("LTRIM "+key+" "+start+" "+end+"\r\n")
  84     connection.readBoolean
  85   }
  86
  87   // LREM
  88   // Remove the first count occurrences of the value element from the list.
  89   def listRem(key: String, count: Int, value: String): Boolean = {
  90     val connection = getConnection(key)
  91     connection.write("LREM "+key+" "+count+" "+value.length+"\r\n"+value+"\r\n")
  92     connection.readBoolean
  93   }
  94 }