#1019 Migrated LPUSH, RPUSH, LPOP, RPOP, LLEN (#1181)

docs/src/content/docs/commands/LLEN.md

@@ -38,6 +38,11 @@ LLEN key
    - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
    - Occurs if the key exists but is not associated with a list.
 
+2. `Wrong number of arguments`
+
+   - Error Message: `(error) ERR wrong number of arguments for 'llen' command`
+   - Occurs if command is executed without any arguments or with 2 or more arguments
+
 ## Example Usage
 
 ### Basic Usage
@@ -64,7 +69,7 @@ Getting the `LLEN` of a list `nonExistentList` which does not exist.
 (integer) 0
 ```
 
-### Invalid usage
+### Invalid Usage: Key is Not a List
 
 Trying to get the `LLEN` of a key `mystring` which is holding wrong data type `string`.
 

docs/src/content/docs/commands/LPOP.md

@@ -17,26 +17,32 @@ LPOP key
 | --------- | ------------------------------------------------------------------------------ | ------ | -------- |
 | `key`     | The key of the list from which the first element will be removed and returned. | String | Yes      |
 
+
+
 ## Return Value
 
-| Condition                                      | Return Value                                                                              |
-| ---------------------------------------------- | ----------------------------------------------------------------------------------------- |
-| Command is successful                          | `String` The value of the first element in the list, if the list exists and is not empty. |
-| If the key does not exist or the list is empty | `nil`                                                                                     |
-| Syntax or specified constraints are invalid    | error                                                                                     |
+| Condition                    | Return Value                                         |
+| ---------------------------- | ---------------------------------------------------- |
+| Command is successful        | `String` The value of the first element in the list. |
+| If the key does not exist    | `nil`                                                |
+| The key is of the wrong type | error                                                |
+
+
 
 ## Behavior
 
-- When the `LPOP` command is executed, DiceDB checks if the key exists and is associated with a list. If so, the first element of the list is removed and returned.
-- If the key does not exist or the list is empty, the command returns `nil`.
+- When the `LPOP` command is executed, DiceDB checks if the key exists and is associated with a list. 
+- If the list has elements, the first element is removed and returned.
+- If the key does not exist, the command treats it as an empty list and returns `nil`.
 - If the key exists but is not associated with a list, a `WRONGTYPE` error is returned.
-- If more than one argument is passed, an error is returned.
+- If more than one key is passed, an error is returned.
 
 ## Errors
 
-1. `Wrong type of key`
+1. `Wrong type of value or key`:
 
-When the `LPOP` command is executed for a key that exists but is not associated with a list, an error is returned. This error occurs if the key is associated with a type other than a list, such as a string or set.
+   - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
+   - Occurs if the key exists but is not associated with a list.
 
 ```bash
 127.0.0.1:7379> LPOP mystring
@@ -45,17 +51,8 @@ When the `LPOP` command is executed for a key that exists but is not associated
 
 2. `Wrong number of arguments`
 
-If the `LPOP` command is executed with more than one key or no key, the following error is returned:
-
-```bash
-127.0.0.1:7379> LPOP
-(error) ERR wrong number of arguments for 'lpop' command
-```
-
-```bash
-127.0.0.1:7379> LPOP mylist secondlist
-(error) ERR wrong number of arguments for 'lpop' command
-```
+   - Error Message: `(error) ERR wrong number of arguments for 'lpop' command`
+   - Occurs if command is executed without any arguments or with 2 or more arguments
 
 ## Example Usage
 
@@ -85,32 +82,27 @@ LPOP mylist
 
 The list `mylist` now contains \["three"\].
 
-### Empty List or Non-Existent Key
+### Non-Existent Key
 
-Returns `(nil)` if the list is empty or the provided key is non-existent
+Returns `(nil)` if the provided key is non-existent
 
 ```bash
 LPOP emptylist
 (nil)
 ```
 
-### Key is Not a List
+### Invalid Usage: Key is Not a List
 
-Setting a key `mystring` with the value `hello`:
+Trying to `LPOP` a key `mystring` which is holding wrong data type `string`.
 
 ```bash
 SET mystring "hello"
 OK
-```
-
-Executing `LPOP` command on any key that is not associated with a List type will result in an error:
-
-```bash
 LPOP mystring
 (error) WRONGTYPE Operation against a key holding the wrong kind of value
 ```
 
-### Wrong Number of Arguments
+### Invalid Usage: Wrong Number of Arguments
 
 Passing more than one key will result in an error:
 
@@ -119,17 +111,10 @@ LPOP mylist secondlist
 (error) ERR wrong number of arguments for 'lpop' command
 ```
 
-### Notes
-
-- The key used with the `LPOP` command should be associated with a list to avoid any potential errors.
-- Use the `EXISTS` command to check if a key exists before using `LPOP` to handle cases where the key might not exist.
-- Consider using `LLEN` to check the length of the list if you need to handle empty lists differently.
-
-## Related Commands
+## Best Practices
 
-- `RPUSH`: Append one or multiple elements to the end of a list.
-- `LPUSH`: Prepend one or multiple elements to the beginning of a list.
-- `RPOP`: Remove and return the last element of a list.
-- `LRANGE`: Get a range of elements from a list.
+- `Check Key Type`: Before using `LPOP`, ensure that the key is associated with a list to avoid errors.
+- `Handle Non-Existent Keys`: Be prepared to handle the case where the key does not exist, as `LPOP` will return `nil` in such scenarios.
+- `Use in Conjunction with Other List Commands`: The `LPOP` command is often used alongside other list commands like `RPUSH`, `LPUSH`, `LLEN`, and `RPOP` to manage and process lists effectively.
 
 By understanding and using the `LPOP` command effectively, you can manage list data structures in DiceDB efficiently, implementing queue-like behaviors and more.

docs/src/content/docs/commands/LPUSH.md

@@ -16,7 +16,7 @@ LPUSH key value [value ...]
 | Parameter          | Description                                                                               | Type   | Required |
 | ------------------ | ----------------------------------------------------------------------------------------- | ------ | -------- |
 | `key`              | The name of the list where values are inserted. If it does not exist, it will be created. | String | Yes      |
-| `value [value...]` | One or more values to be inserted at the head of the list.                                | String | Yes      |
+| `value [value...]` | One or more space separated values to be inserted at the head of the list.                | String | Yes      |
 
 ## Return Value
 
@@ -46,7 +46,7 @@ LPUSH key value [value ...]
 
 ## Example Usage
 
-### Single Value Insertion
+### Basic Usage
 
 Insert the value `world` at the head of the list stored at key `mylist`. If `mylist` does not exist, a new list is created.
 
@@ -55,7 +55,7 @@ Insert the value `world` at the head of the list stored at key `mylist`. If `myl
 (integer) 1
 ```
 
-### Multiple Values Insertion
+### Inserting Multiple Values
 
 Insert the value `hello` and `world` at the head of the list stored at key `mylist`. After execution, `world` will be the first element, followed by `hello`.
 
@@ -75,7 +75,7 @@ Create a new list with the key `newlist` and inserts the value `first` at the he
 (integer) 1
 ```
 
-### Error: Wrong Type
+### Invalid Usage: Key is Not a List
 
 Insert the value `value` at the head of the key `mystring`, which stores a string, not a list.
 
@@ -86,9 +86,19 @@ OK
 (error) WRONGTYPE Operation against a key holding the wrong kind of value
 ```
 
-## Notes
+### Invalid Usage: Wrong Number of Arguments
 
-- The `LPUSH` command is often used in conjunction with the `RPUSH` command, which inserts values at the tail (right) of the list.
+Calling `LPUSH` without passing any values:
+
+```bash
+LPUSH mylist
+(error) ERR wrong number of arguments for 'lpush' command
+```
+
+## Best Practices
+
+- `Check Key Type`: Before using `LPUSH`, ensure that the key is associated with a list to avoid errors.
+- `Use in Conjunction with Other List Commands`: The `LPUSH` command is often used alongside other list commands like `RPUSH`, `LLEN`, `LPOP`, and `RPOP` to manage and process lists effectively.
 - The `LPUSH` command can be used to implement a stack (LIFO) by always pushing new elements to the head of the list.
 
 By understanding the `LPUSH` command, you can efficiently manage lists in DiceDB, ensuring that elements are added to the head of the list as needed.

docs/src/content/docs/commands/RPOP.md

@@ -17,35 +17,39 @@ RPOP key
 | --------- | ---------------------------------------------------------------- | ------ | -------- |
 | `key`     | The key of the list from which the last element will be removed. | String | Yes      |
 
+
 ## Return values
 
-| Condition                                   | Return Value                                                               |
-| ------------------------------------------- | -------------------------------------------------------------------------- |
-| The command is successful                   | The value of the last element in the list                                  |
-| The list is empty or the key does not exist | `nil`                                                                      |
-| The key is of the wrong type                | Error: `WRONGTYPE Operation against a key holding the wrong kind of value` |
+| Condition                    | Return Value                                       |
+| ---------------------------- | -------------------------------------------------- |
+| The command is successful    | `String` The value of the last element in the list |
+| The key does not exist       | `nil`                                              |
+| The key is of the wrong type | error                                              |
+
 
 ## Behaviour
 
-- The `RPOP` command checks if the key exists and whether it contains a list.
-- If the key does not exist, the command treats it as an empty list and returns `nil`.
-- If the key exists but the list is empty, `nil` is returned.
+- When the `RPOP` command is executed, DiceDB checks if the key exists and is associated with a list. 
 - If the list has elements, the last element is removed and returned.
-- If the key exists but is not of type list, an error is raised.
+- If the key does not exist, the command treats it as an empty list and returns `nil`.
+- If the key exists but is not associated with a list, a `WRONGTYPE` error is returned.
+- If more than one key is passed, an error is returned.
 
 ## Errors
 
-1. **Wrong type of value or key**:
+1. `Wrong type of value or key`:
 
    - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
-   - Occurs when attempting to run `RPOP` on a key that is not a list.
+   - Occurs if the key exists but is not associated with a list.
+
+2. `Wrong number of arguments`
 
-2. **Non-existent or empty list**:
-   - Returns `nil` when the key does not exist or the list is empty.
+   - Error Message: `(error) ERR wrong number of arguments for 'lpop' command`
+   - Occurs if command is executed without any arguments or with 2 or more arguments
 
 ## Example Usage
 
-### Example 1: Basic Usage
+### Basic Usage
 
 ```bash
 127.0.0.1:7379> LPUSH mylist "one" "two" "three"
@@ -54,30 +58,38 @@ RPOP key
 "one"
 ```
 
-### Example 2: Empty List
+### Non-Existent Key
+
+Returns `(nil)` if the provided key is non-existent
 
 ```bash
 127.0.0.1:7379> RPOP emptylist
 (nil)
 ```
 
-### Example 3: Non-List Key
+### Invalid Usage: Key is Not a List
+
+Trying to `LPOP` a key `mystring` which is holding wrong data type `string`.
 
 ```bash
-127.0.0.1:7379> SET mystring "Hello"
+SET mystring "hello"
 OK
-127.0.0.1:7379> RPOP mystring
+LPOP mystring
 (error) WRONGTYPE Operation against a key holding the wrong kind of value
 ```
 
-## Notes
+### Invalid Usage: Wrong Number of Arguments
 
-- The `RPOP` command is atomic, meaning it is safe to use in concurrent environments.
-- If you need to remove and return the first element of the list, use the `LPOP` command instead.
+Passing more than one key will result in an error:
 
-## Related Commands
+```bash
+RPOP mylist secondlist
+(error) ERR wrong number of arguments for 'lpop' command
+```
 
-- `LPUSH`: Insert all the specified values at the head of the list stored at key.
-- `LPOP`: Removes and returns the first element of the list stored at key.
+## Best Practices
+- `Check Key Type`: Before using `RPOP`, ensure that the key is associated with a list to avoid errors.
+- `Handle Non-Existent Keys`: Be prepared to handle the case where the key does not exist, as `RPOP` will return `nil` in such scenarios.
+- `Use in Conjunction with Other List Commands`: The `RPOP` command is often used alongside other list commands like `RPUSH`, `LPUSH`, `LLEN`, and `LPOP` to manage and process lists effectively.
 
 By understanding the `RPOP` command, you can effectively manage lists in DiceDB, ensuring that you can retrieve and process elements in a LIFO order.

docs/src/content/docs/commands/RPUSH.md

@@ -13,17 +13,18 @@ RPUSH key value [value ...]
 
 ## Parameters
 
-| Parameter | Description                                                                                                       | Type   | Required |
-| --------- | ----------------------------------------------------------------------------------------------------------------- | ------ | -------- |
-| `key`     | The name of the list where the values will be inserted. If the list does not exist, a new list will be created.   | String | Yes      |
-| `value`   | One or more values to be inserted at the tail of the list. Multiple values can be specified, separated by spaces. | String | Yes      |
+| Parameter          | Description                                                                               | Type   | Required |
+| ------------------ | ----------------------------------------------------------------------------------------- | ------ | -------- |
+| `key`              | The name of the list where values are inserted. If it does not exist, it will be created. | String | Yes      |
+| `value [value...]` | One or more space separated values to be inserted at the tail of the list.                | String | Yes      |
+
 
 ## Return Value
 
-| Condition                                   | Return Value |
-| ------------------------------------------- | ------------ |
-| Command is successful                       | integer      |
-| Syntax or specified constraints are invalid | error        |
+| Condition                                   | Return Value                                   |
+| ------------------------------------------- | ---------------------------------------------- |
+| Command is successful                       | `Integer` - length of the list after execution |
+| Syntax or specified constraints are invalid | error                                          |
 
 ## Behaviour
 
@@ -34,14 +35,15 @@ RPUSH key value [value ...]
 
 ## Errors
 
-1. `Non-List Key`: If the key exists but is not a list, DiceDB returns an error.
+1. `Wrong Number of Arguments`
 
-   - Error Message: `WRONGTYPE Operation against a key holding the wrong kind of value`
-   - Occurs when trying to use the command on a key that does not contain a list.
+    - Error Message: `(error) ERR wrong number of arguments for 'rpush' command`
+    - Occurs if the key parameters is not provided or at least one value is not provided. 
 
-2. `Invalid Syntax`: If the command is not used with the correct syntax, DiceDB returns a syntax error.
-   - Error Message: `ERR wrong number of arguments for 'rpush' command`
-   - Occurs if the command's syntax is incorrect, like wrong number of arguments.
+2. `Wrong Type of Key or Value`: 
+
+   - Error Message: `(error) WRONGTYPE Operation against a key holding the wrong kind of value`
+   - Occurs if the key exists and is not a list. DiceDB expects the key to either be non-existent or to hold a list data type.
 
 ## Example Usage
 
@@ -60,22 +62,30 @@ Inserting multiple values `world`, `foo`, `bar` into `mylist`
 
 ```bash
 127.0.0.1:7379> RPUSH mylist "world" "foo" "bar"
-(integer) 4
+(integer) 3
 ```
 
-### Invalid Usage
+### Invalid Usage: Key is Not a List
 
-Trying to insert value `val` into a non-list type `mykey`
+Insert the value `value` at the tail of the key `mystring`, which stores a string, not a list.
 
-```bash
-127.0.0.1:7379> SET mykey "notalist"
-127.0.0.1:7379> RPUSH mykey "val"
-(error) ERROR WRONGTYPE Operation against a key holding the wrong kind of value
+```shell
+127.0.0.1:7379> SET mystring "not a list"
+OK
+127.0.0.1:7379> RPUSH mystring "value"
+(error) WRONGTYPE Operation against a key holding the wrong kind of value
 ```
 
-Trying to run `rpush` with only 1 argument
+### Invalid Usage: Wrong Number of Arguments
+
+Calling `RPUSH` without passing any values:
 
 ```bash
-127.0.0.1:7379> RPUSH mylist
-(error) ERROR wrong number of arguments
+RPUSH mylist
+(error) ERR wrong number of arguments for 'rpush' command
 ```
+
+## Best Practices
+
+- `Check Key Type`: Before using `RPUSH`, ensure that the key is associated with a list to avoid errors.
+- `Use in Conjunction with Other List Commands`: The `RPUSH` command is often used alongside other list commands like `LLEN`, `LPUSH`, `LPOP`, and `RPOP` to manage and process lists effectively.