1. A method of processing an input comprising: providing a graphical representation of a finite state machine including states and transitions between said states representing a syntax used for determining whether the input is syntactically valid, said graphical representation of said finite state machine including elements representing said states and said transitions between said states; generating, from said graphical representation, a second representation corresponding to said graphical representation; generating, using said second representation, parser source code, wherein said generating the parser source code further includes: generating code for an outer processing loop and a switch statement included within the outer processing loop whereby the switch statement switches between different cases based on a value of a parsing state variable, each of the different cases corresponding to a different parsing state; for each of the different cases corresponding to a different parsing state included in the second representation, performing first processing to generate code for the different parsing state as a case of the switch statement, said first processing including: determining a set of valid next tokens causing a state transition from the different parsing state; generating code to process each of the valid next tokens in the set; and determining a next parsing state included in the second representation for which said first processing is performed; and generating code for a default case of the switch statement corresponding to an error state; processing the parser source code to generate parser executable code for a parser used for parsing the input to determine its syntactic validity in accordance with said syntax, wherein processing the parser source code includes compiling the parser source code; parsing the input using the parser, wherein said parsing includes executing the parser executable code for the parser generated from the parser source code; responsive to said parsing and the input being syntactically correct, generating an intermediate representation of the input, and wherein said syntax is a first of a plurality of syntaxes, said parser is one of a plurality of parsers, a command is expressed in a plurality of different representations corresponding to said plurality of syntaxes, said input is one of the plurality of different representations of said command, and wherein each of said plurality of parsers parses one of the plurality of different representations of the command and generates a same intermediate representation that is said intermediate representation.