parse.c

早期freebsd实现

 * Side Effects:
 *---------------------------------------------------------------------
 */
static int
ParseReadc()
{
    if (curFILE)
	return fgetc(curFILE);
	  
    if (curPTR && *curPTR->ptr)
	return *curPTR->ptr++;
    return EOF;
}


/*-
 *---------------------------------------------------------------------
 * ParseUnreadc  --
 *	Put back a character to the current file 
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *---------------------------------------------------------------------
 */
static void
ParseUnreadc(c)
    int c;
{
    if (curFILE) {
	ungetc(c, curFILE);
	return;
    }
    if (curPTR) {
	*--(curPTR->ptr) = c;
	return;
    }
}


/* ParseSkipLine():
 *	Grab the next line
 */
static char *
ParseSkipLine(skip)
    int skip; 		/* Skip lines that don't start with . */
{
    char *line;
    int c, lastc = '\0', lineLength;
    Buffer buf;

    c = ParseReadc();

    if (skip) {
	/*
	 * Skip lines until get to one that begins with a
	 * special char.
	 */
	while ((c != '.') && (c != EOF)) {
	    while (((c != '\n') || (lastc == '\\')) && (c != EOF))
	    {
		/*
		 * Advance to next unescaped newline
		 */
		if ((lastc = c) == '\n') {
		    lineno++;
		}
		c = ParseReadc();
	    }
	    lineno++;
	    
	    lastc = c;
	    c = ParseReadc ();
	}
    }
    
    if (c == EOF) {
	Parse_Error (PARSE_FATAL, "Unclosed conditional/for loop");
	return ((char *)NULL);
    }
    
    /*
     * Read the entire line into buf
     */
    buf = Buf_Init (MAKE_BSIZE);
    if (c != '\n') {
	do {
	    Buf_AddByte (buf, (Byte)c);
	    c = ParseReadc();
	} while ((c != '\n') && (c != EOF));
    }
    lineno++;
    
    Buf_AddByte (buf, (Byte)'\0');
    line = (char *)Buf_GetAll (buf, &lineLength);
    Buf_Destroy (buf, FALSE);
    return line;
}


/*-
 *---------------------------------------------------------------------
 * ParseReadLine --
 *	Read an entire line from the input file. Called only by Parse_File.
 *	To facilitate escaped newlines and what have you, a character is
 *	buffered in 'lastc', which is '\0' when no characters have been
 *	read. When we break out of the loop, c holds the terminating
 *	character and lastc holds a character that should be added to
 *	the line (unless we don't read anything but a terminator).
 *
 * Results:
 *	A line w/o its newline
 *
 * Side Effects:
 *	Only those associated with reading a character
 *---------------------------------------------------------------------
 */
static char *
ParseReadLine ()
{
    Buffer  	  buf;	    	/* Buffer for current line */
    register int  c;	      	/* the current character */
    register int  lastc;    	/* The most-recent character */
    Boolean	  semiNL;     	/* treat semi-colons as newlines */
    Boolean	  ignDepOp;   	/* TRUE if should ignore dependency operators
				 * for the purposes of setting semiNL */
    Boolean 	  ignComment;	/* TRUE if should ignore comments (in a
				 * shell command */
    char    	  *line;    	/* Result */
    int	    	  lineLength;	/* Length of result */

    semiNL = FALSE;
    ignDepOp = FALSE;
    ignComment = FALSE;

    /*
     * Handle special-characters at the beginning of the line. Either a
     * leading tab (shell command) or pound-sign (possible conditional)
     * forces us to ignore comments and dependency operators and treat
     * semi-colons as semi-colons (by leaving semiNL FALSE). This also
     * discards completely blank lines.
     */
    for (;;) {
	c = ParseReadc();

	if (c == '\t') {
	    ignComment = ignDepOp = TRUE;
	    break;
	} else if (c == '\n') {
	    lineno++;
	} else if (c == '#') {
	    ParseUnreadc(c);
	    break;
	} else {
	    /*
	     * Anything else breaks out without doing anything
	     */
	    break;
	}
    }
	
    if (c != EOF) {
	lastc = c;
	buf = Buf_Init(MAKE_BSIZE);
	
	while (((c = ParseReadc ()) != '\n' || (lastc == '\\')) &&
	       (c != EOF))
	{
test_char:
	    switch(c) {
	    case '\n':
		/*
		 * Escaped newline: read characters until a non-space or an
		 * unescaped newline and replace them all by a single space.
		 * This is done by storing the space over the backslash and
		 * dropping through with the next nonspace. If it is a
		 * semi-colon and semiNL is TRUE, it will be recognized as a
		 * newline in the code below this...
		 */
		lineno++;
		lastc = ' ';
		while ((c = ParseReadc ()) == ' ' || c == '\t') {
		    continue;
		}
		if (c == EOF || c == '\n') {
		    goto line_read;
		} else {
		    /*
		     * Check for comments, semiNL's, etc. -- easier than
		     * ParseUnreadc(c); continue;
		     */
		    goto test_char;
		}
		/*NOTREACHED*/
		break;

	    case ';':
		/*
		 * Semi-colon: Need to see if it should be interpreted as a
		 * newline
		 */
		if (semiNL) {
		    /*
		     * To make sure the command that may be following this
		     * semi-colon begins with a tab, we push one back into the
		     * input stream. This will overwrite the semi-colon in the
		     * buffer. If there is no command following, this does no
		     * harm, since the newline remains in the buffer and the
		     * whole line is ignored.
		     */
		    ParseUnreadc('\t');
		    goto line_read;
		} 
		break;
	    case '=':
		if (!semiNL) {
		    /*
		     * Haven't seen a dependency operator before this, so this
		     * must be a variable assignment -- don't pay attention to
		     * dependency operators after this.
		     */
		    ignDepOp = TRUE;
		} else if (lastc == ':' || lastc == '!') {
		    /*
		     * Well, we've seen a dependency operator already, but it
		     * was the previous character, so this is really just an
		     * expanded variable assignment. Revert semi-colons to
		     * being just semi-colons again and ignore any more
		     * dependency operators.
		     *
		     * XXX: Note that a line like "foo : a:=b" will blow up,
		     * but who'd write a line like that anyway?
		     */
		    ignDepOp = TRUE; semiNL = FALSE;
		}
		break;
	    case '#':
		if (!ignComment) {
		    if (compatMake || (lastc != '\\')) {
			/*
			 * If the character is a hash mark and it isn't escaped
			 * (or we're being compatible), the thing is a comment.
			 * Skip to the end of the line.
			 */
			do {
			    c = ParseReadc();
			} while ((c != '\n') && (c != EOF));
			goto line_read;
		    } else {
			/*
			 * Don't add the backslash. Just let the # get copied
			 * over.
			 */
			lastc = c;
			continue;
		    }
		}
		break;
	    case ':':
	    case '!':
		if (!ignDepOp && (c == ':' || c == '!')) {
		    /*
		     * A semi-colon is recognized as a newline only on
		     * dependency lines. Dependency lines are lines with a
		     * colon or an exclamation point. Ergo...
		     */
		    semiNL = TRUE;
		}
		break;
	    }
	    /*
	     * Copy in the previous character and save this one in lastc.
	     */
	    Buf_AddByte (buf, (Byte)lastc);
	    lastc = c;
	    
	}
    line_read:
	lineno++;
	
	if (lastc != '\0') {
	    Buf_AddByte (buf, (Byte)lastc);
	}
	Buf_AddByte (buf, (Byte)'\0');
	line = (char *)Buf_GetAll (buf, &lineLength);
	Buf_Destroy (buf, FALSE);
	
	if (line[0] == '.') {
	    /*
	     * The line might be a conditional. Ask the conditional module
	     * about it and act accordingly
	     */
	    switch (Cond_Eval (line)) {
	    case COND_SKIP:
		/*
		 * Skip to next conditional that evaluates to COND_PARSE.
		 */
		do {
		    free (line);
		    line = ParseSkipLine(1);
		} while (line && Cond_Eval(line) != COND_PARSE);
		if (line == NULL)
		    break;
		/*FALLTHRU*/
	    case COND_PARSE:
		free ((Address) line);
		line = ParseReadLine();
		break;
	    case COND_INVALID:
		if (For_Eval(line)) {
		    int ok;
		    free(line);
		    do {
			/*
			 * Skip after the matching end
			 */
			line = ParseSkipLine(0);
			if (line == NULL) {
			    Parse_Error (PARSE_FATAL, 
				     "Unexpected end of file in for loop.\n");
			    break;
			}
			ok = For_Eval(line);
			free(line);
		    }
		    while (ok);
		    if (line != NULL)
			For_Run();
		    line = ParseReadLine();
		}
		break;
	    }
	}
	return (line);

    } else {
	/*
	 * Hit end-of-file, so return a NULL line to indicate this.
	 */
	return((char *)NULL);
    }
}

/*-
 *-----------------------------------------------------------------------
 * ParseFinishLine --
 *	Handle the end of a dependency group.
 *
 * Results:
 *	Nothing.
 *
 * Side Effects:
 *	inLine set FALSE. 'targets' list destroyed.
 *
 *-----------------------------------------------------------------------
 */
static void
ParseFinishLine()
{
    extern int Suff_EndTransform();

    if (inLine) {
	Lst_ForEach(targets, Suff_EndTransform, (ClientData)NULL);
	Lst_Destroy (targets, ParseHasCommands);
	inLine = FALSE;
    }
}
		    

/*-
 *---------------------------------------------------------------------
 * Parse_File --
 *	Parse a file into its component parts, incorporating it into the
 *	current dependency graph. This is the main function and controls
 *	almost every other function in this module
 *
 * Results:
 *	None
 *
 * Side Effects:
 *	Loads. Nodes are added to the list of all targets, nodes and links
 *	are added to the dependency graph. etc. etc. etc.
 *---------------------------------------------------------------------
 */
void
Parse_File(name, stream)
    char          *name;	/* the name of the file being read */
    FILE *	  stream;   	/* Stream open to makefile to parse */
{
    register char *cp,		/* pointer into the line */
                  *line;	/* the line we're working on */

    inLine = FALSE;
    fname = name;
    curFILE = stream;
    lineno = 0;
    fatals = 0;

    do {
	while ((line = ParseReadLine ()) != NULL) {
	    if (*line == '.') {
		/*
		 * Lines that begin with the special character are either
		 * include or undef directives.
		 */
		for (cp = line + 1; isspace (*cp); cp++) {
		    continue;
		}
		if (strncmp (cp, "include", 7) == 0) {
		    ParseDoInclude (cp + 7);
		    goto nextLine;
		} else if (strncmp(cp, "undef", 5) == 0) {
		    char *cp2;
		    for (cp += 5; isspace(*cp); cp++) {
			continue;
		    }

		    for (cp2 = cp; !isspace(*cp2) && (*cp2 != '\0'); cp2++) {
			continue;
		    }

		    *cp2 = '\0';

		    Var_Delete(cp, VAR_GLOBAL);
		    goto nextLine;
		}
	    }
	    if (*line == '#') {
		/* If we're this far, the line must be a comment. */
		goto nextLine;
	    }
	    
	    if (*line == '\t'
#ifdef POSIX
		       || *line == ' '
#endif
		       )
	    {
		/*
		 * If a line starts with a tab (or space in POSIX-land), it
		 * can only hope to be a creation command.
		 */
	    shellCommand:
		for (cp = line + 1; isspace (*cp); cp++) {
		    continue;
		}
		if (*cp) {
		    if (inLine) {
			/*
			 * So long as it's not a blank line and we're actually
			 * in a dependency spec, add the command to the list of
			 * commands of all targets in the dependency spec 
			 */
			Lst_ForEach (targets, ParseAddCmd, (ClientData)cp);
			continue;
		    } else {
			Parse_Error (PARSE_FATAL,
				     "Unassociated shell command \"%.20s\"",
				     cp);
		    }
		}
#ifdef SYSVINCLUDE
	    } else if (strncmp (line, "include", 7) == 0 && 
		       strchr(line, ':') == NULL) {
		/*
		 * It's an S3/S5-style "include".
		 */
		ParseTraditionalInclude (line + 7);
		goto nextLine;
#endif
	    } else if (Parse_IsVar (line)) {
		ParseFinishLine();
		Parse_DoVar (line, VAR_GLOBAL);
	    } else {
		/*
		 * We now know it's a dependency line so it needs to have all
		 * variables expanded before being parsed. Tell the variable
		 * module to complain if some variable is undefined...
		 * To make life easier on novices, if the line is indented we
		 * first make sure the line has a dependency operator in it.
		 * If it doesn't have an operator and we're in a dependency
		 * line's script, we assume it's actually a shell command