I wrote a parser grammar in ANTLR4 which looks like this:

parser grammar IFJ23;

tokens {
    Identifier, Type,
    LeftBracket, RightBracket,
    LeftCurlyBracket, RightCurlyBracket,
    Semicolon, Colon, Arrow, Comma,

    /** Keywords */
    FunctionKeyword
}

swiftFile
    : functionDeclaration swiftFile
    ;



/** Statements */
statement
    : declaration Semicolon?
    ;

statements
    : statement statements?
    ;

codeBlock
    : LeftCurlyBracket statements? RightCurlyBracket
    ;



/** Declarations */
declaration
    : functionDeclaration
//    | variableDeclaration
    ;



/** Function declarations */
functionDeclaration
    : FunctionKeyword Identifier functionSignature functionBody
    ;

functionSignature
    : parameterClause functionResult?
    ;

functionBody
    : codeBlock
    ;

parameterClause
    : LeftBracket RightBracket
    | LeftBracket parameterList RightBracket
    ;

functionResult
    : Arrow Type
    ;

parameterList
    : parameter
    | parameter Comma parameterList
    ;

parameter
    : externalParameterName? localParameterName typeAnnotation
    ;

externalParameterName
    : Identifier
    ;

localParameterName
    : Identifier
    ;

typeAnnotation
    : Colon Type
    ;

Now, the problem I am facing is that I already have a functional lexer that is not written in ANTLR4. It's written in C and it generates a list of tokens for a file.

Is there a way to somehow make ANTLR4 accept this token list as input and try to generate a parse tree?

I would also need to match the tokens in the Tokens {} list with their respective token types generated from my lexer.