【C】CDECL 源代码

#include 
#include 
#include 
#include 

#define MAXTOKENS 100
#define MAXTOKENLEN 64

enum type_tag { IDENTIFIER, QUALIFIER, TYPE };

struct token 
{
	char type;
	char string[MAXTOKENLEN];
};

int top = -1;
struct token stack[MAXTOKENS];
struct token This;

#define pop stack[top--]
#define push(s) stack[++top] = s

/* figure out the identifier type */
enum type_tag classify_string(void)
{
	char *s = This.string;
	if (!strcmp(s, "const"))
	{
		strcpy(s, "read-only");
		return QUALIFIER;
	}
	if (!strcmp(s, "volatile"))
		return QUALIFIER;
	if (!strcmp(s, "void"))
		return TYPE;
	if (!strcmp(s, "char"))
		return TYPE;
	if (!strcmp(s, "signed"))
		return TYPE;
	if (!strcmp(s, "unsigned"))
		return TYPE;
	if (!strcmp(s, "short"))
		return TYPE;
	if (!strcmp(s, "int"))
		return TYPE;
	if (!strcmp(s, "long"))
		return TYPE;
	if (!strcmp(s, "float"))
		return TYPE;
	if (!strcmp(s, "double"))
		return TYPE;
	if (!strcmp(s, "struct"))
		return TYPE;
	if (!strcmp(s, "union"))
		return TYPE;
	if (!strcmp(s, "enum"))
		return TYPE;
	return IDENTIFIER;
}

/* read next token into "this" */
void gettoken(void)
{
	char *p = This.string;

	/* read past any space */
	while ((*p = getchar()) == ' ');

	if (isalnum(*p))
	{
		/* it starts with A-Z, 0-9 read in identifier */
		while (isalnum(*++p = getchar()));
		ungetc(*p, stdin);
		*p = '\0';
		This.type = classify_string();
		return;
	}

	if (*p == '*')
	{
		strcpy(This.string, "pointer to");
		This.type = '*';
		return;
	}
	This.string[1] = '\0';
	This.type = *p;
	return;
}

/* the piece of code that understandeth all parsing */
void read_to_first_identifier()
{
	gettoken();
	while (This.type != IDENTIFIER )
	{
		push(This);
		gettoken();
	}
	printf("%s is ", This.string);
	gettoken();
}

void deal_with_arrays()
{
	while (This.type == '[')
	{
		printf("array ");
		gettoken(); /* a number or ']' */
		if (isdigit(This.string[0]))
		{
			printf("0..%d ", atoi(This.string) - 1);
			gettoken(); /* read the ']' */
		}
		gettoken(); /* read next past the ']' */
		printf("of ");
	}
}

void deal_with_function_args()
{
	while (This.type != ')')
	{
		gettoken();
	}
	gettoken();
	printf("function returning ");
}

void deal_with_pointers()
{
	while (stack[top].type == '*')
	{
		printf("%s ", pop.string);
	}
}

void deal_with_declarator()
{
	/* deal with possible array/function following identifier */
	switch (This.type)
	{
	case '[' : deal_with_arrays(); break;
	case '(' : deal_with_function_args();
	}

	deal_with_pointers();

	/* process tokens that we stacked while reading identifier */
	while (top >= 0)
	{
		if (stack[top].type == '(')
		{
			pop;
			gettoken(); /* read past ')' */
			deal_with_declarator();
		}
		else
		{
			printf("%s ", pop.string);
		}
	}
}

int main()
{
	/* put tokens on stack until we reach identifier */
	read_to_first_identifier();
	deal_with_declarator();
	printf("\n");

	return 0;
}

以上是C语言版本。。