oberonjs/test/examples/String.ob

MODULE String;
CONST
    offs8 = 8;
    offs16 = 8 + 16;
    offs32 = offs16 + 32;
    offs64 = offs32 + 64;
    offs128 = offs64 + 128;
    offs256 = offs128 + 256;
    offs512 = offs256 + 512;
    offs1024 = offs512 + 1024;
    chunkSize = 4096;
TYPE
    Type* = POINTER TO RECORD
        size: INTEGER;
        data: ARRAY 8 OF CHAR;
        next: POINTER TO Data16
    END;
    Data16 = RECORD
        data: ARRAY 16 OF CHAR;
        next: POINTER TO Data32
    END;
    Data32 = RECORD
        data: ARRAY 32 OF CHAR;
        next: POINTER TO Data64
    END;
    Data64 = RECORD
        data: ARRAY 64 OF CHAR;
        next: POINTER TO Data128
    END;
    Data128 = RECORD
        data: ARRAY 128 OF CHAR;
        next: POINTER TO Data256
    END;
    Data256 = RECORD
        data: ARRAY 256 OF CHAR;
        next: POINTER TO Data512
    END;
    Data512 = RECORD
        data: ARRAY 512 OF CHAR;
        next: POINTER TO Data1024
    END;
    Data1024 = RECORD
        data: ARRAY 1024 OF CHAR;
        next: POINTER TO Chunk
    END;
    Chunk = RECORD
        data: ARRAY chunkSize OF CHAR;
        next: POINTER TO Chunk
    END;

PROCEDURE fromArray*(a: ARRAY OF CHAR): Type;
VAR 
    result: Type;
    
    PROCEDURE copy(from: INTEGER; VAR dst: ARRAY OF CHAR): BOOLEAN;
    VAR
        i: INTEGER;
    BEGIN
        WHILE (i < LEN(dst)) & (i + from < LEN(a)) DO
            dst[i] := a[i + from];
            INC(i);
        END;
        RETURN i + from < LEN(a)
    END copy;

    PROCEDURE copyToChunks();
    VAR
        i: INTEGER;
        from: INTEGER;
        chunk: POINTER TO Chunk;
    BEGIN
        from := offs1024;
        NEW(chunk); 
        result.next.next.next.next.next.next.next.next := chunk;
        WHILE from < LEN(a) DO
            IF i = LEN(chunk.data) THEN
                NEW(chunk.next);
                chunk := chunk.next;
                i := 0;
            END;
            chunk.data[i] := a[from];
            INC(i);
            INC(from);
        END;
    END copyToChunks;

BEGIN
    NEW(result);
    IF copy(0, result.data) THEN
        NEW(result.next);
        IF copy(offs8, result.next.data) THEN
            NEW(result.next.next);
            IF copy(offs16, result.next.next.data) THEN
                NEW(result.next.next.next);
                IF copy(offs32, result.next.next.next.data) THEN
                    NEW(result.next.next.next.next);
                    IF copy(offs64, result.next.next.next.next.data) THEN
                        NEW(result.next.next.next.next.next);
                        IF copy(offs128, result.next.next.next.next.next.data) THEN
                            NEW(result.next.next.next.next.next.next);
                            IF copy(offs256, result.next.next.next.next.next.next.data) THEN
                                NEW(result.next.next.next.next.next.next.next);
                                IF copy(offs512, result.next.next.next.next.next.next.next.data) THEN
                                    copyToChunks();
                                END;
                            END;
                        END;
                    END;
                END;
            END;
        END;
    END;

    result.size := LEN(a);
    RETURN result
END fromArray;    

PROCEDURE size*(s: Type): INTEGER;
    RETURN s.size
END size;

PROCEDURE at*(s: Type; index: INTEGER): CHAR;
VAR
    result: CHAR;

    PROCEDURE chunkAt(): CHAR;
    VAR
        i: INTEGER;
        chunk: POINTER TO Chunk;
    BEGIN
        chunk := s.next.next.next.next.next.next.next.next;
        FOR i := 0 TO ((index - offs1024) DIV chunkSize) - 1 DO
            chunk := chunk.next;
        END;
        RETURN chunk.data[(index - offs1024) MOD chunkSize]
    END chunkAt;

BEGIN
    IF index < offs8 THEN
        result := s.data[index];
    ELSIF index < offs16 THEN
        result := s.next.data[index - offs8];
    ELSIF index < offs32 THEN
        result := s.next.next.data[index - offs16];
    ELSIF index < offs64 THEN
        result := s.next.next.next.data[index - offs32];
    ELSIF index < offs128 THEN
        result := s.next.next.next.next.data[index - offs64];
    ELSIF index < offs256 THEN
        result := s.next.next.next.next.next.data[index - offs128];
    ELSIF index < offs512 THEN
        result := s.next.next.next.next.next.next.data[index - offs256];
    ELSIF index < offs1024 THEN
        result := s.next.next.next.next.next.next.next.data[index - offs512];
    ELSE
        result := chunkAt();
    END
    RETURN result
END at;

END String.