1 /*****************************************************************************/
5 /* Input stack for the scanner */
9 /* (C) 2000 Ullrich von Bassewitz */
11 /* D-70597 Stuttgart */
12 /* EMail: uz@musoftware.de */
15 /* This software is provided 'as-is', without any expressed or implied */
16 /* warranty. In no event will the authors be held liable for any damages */
17 /* arising from the use of this software. */
19 /* Permission is granted to anyone to use this software for any purpose, */
20 /* including commercial applications, and to alter it and redistribute it */
21 /* freely, subject to the following restrictions: */
23 /* 1. The origin of this software must not be misrepresented; you must not */
24 /* claim that you wrote the original software. If you use this software */
25 /* in a product, an acknowledgment in the product documentation would be */
26 /* appreciated but is not required. */
27 /* 2. Altered source versions must be plainly marked as such, and must not */
28 /* be misrepresented as being the original software. */
29 /* 3. This notice may not be removed or altered from any source */
32 /*****************************************************************************/
36 #include "../common/xmalloc.h"
43 /*****************************************************************************/
45 /*****************************************************************************/
49 /* Size of the stack (== maximum nested macro or repeat count) */
50 #define ISTACK_MAX 256
52 /* Structure holding a stack element */
53 typedef struct IElement IElement;
55 IElement* Next; /* Next stack element */
56 int (*Func)(void*); /* Function called for input */
57 void* Data; /* User data given as argument */
58 const char* Desc; /* Description */
62 static IElement* IStack = 0; /* Input stack pointer */
63 static unsigned ICount = 0; /* Number of items on the stack */
67 /*****************************************************************************/
69 /*****************************************************************************/
73 void PushInput (int (*Func) (void*), void* Data, const char* Desc)
74 /* Push an input function onto the input stack */
78 /* Check for a stack overflow */
79 if (ICount > ISTACK_MAX) {
83 /* Create a new stack element */
84 E = xmalloc (sizeof (*E));
99 /* Pop the current input function from the input stack */
103 /* We cannot pop from an empty stack */
104 PRECONDITION (IStack != 0);
106 /* Remember the last element */
110 IStack = IStack->Next;
118 int InputFromStack (void)
119 /* Try to get input from the input stack. Return true if we had such input,
120 * return false otherwise.
123 /* Repeatedly call the TOS routine until we have a token or if run out of
127 if (IStack->Func (IStack->Data) != 0) {
128 /* We have a token */
133 /* Nothing is on the stack */
139 void CheckInputStack (void)
140 /* Called from the scanner before closing an input file. Will check for any
141 * stuff on the input stack.
145 Error (ERR_OPEN_STMT, IStack->Desc);