commit 8c246a9dc294760f2a981cf5144fe4939d1554e6
author Jack Palevich <jackpal@google.com> Tue Jul 14 21:14:10 2009 -0700
committer Jack Palevich <jackpal@google.com> Tue Jul 14 21:14:10 2009 -0700
tree 3acddb5c558e29ca12ef29e78c068d88c1b70ba9
parent fd3db48e2e066a36371fbd018082c7f5db8e37e5

Add accRegisterSymbolCallback API to control external symbol linkage.

Until now dlsym was used to lookup external symbols. Now you can
register your own function to be called when an undefined symbol is
used.

libacc/acc.cpp

diff --git a/libacc/acc.cpp b/libacc/acc.cpp
index 119d106..36f30a1 100644
--- a/libacc/acc.cpp
+++ b/libacc/acc.cpp
@@ -3232,6 +3232,8 @@
     char* dptr; // Macro state: Points to macro text during macro playback.
     int dch;    // Macro state: Saves old value of ch during a macro playback.
     char* pGlobalBase;
+    ACCSymbolLookupFn mpSymbolLookupFn;
+    void* mpSymbolLookupContext;
 
     // Arena for the duration of the compile
     Arena mGlobalArena;
@@ -3792,6 +3794,7 @@
         }
         return false;
     }
+
     /* Parse and evaluate a unary expression.
      * allowAssignment is true if '=' parsing wanted (quick hack)
      */
@@ -3880,9 +3883,12 @@
                 }
                 VariableInfo* pVI = VI(t);
                 n = (intptr_t) pVI->pAddress;
-                /* forward reference: try dlsym */
+                /* forward reference: try our lookup function */
                 if (!n) {
-                    n = (intptr_t) dlsym(RTLD_DEFAULT, nameof(t));
+                    if (mpSymbolLookupFn) {
+                        n = (intptr_t) mpSymbolLookupFn(
+                            mpSymbolLookupContext, nameof(t));
+                    }
                     if (pVI->pType == NULL) {
                         if (tok == '(') {
                             pVI->pType = mkpIntFn;
@@ -4613,6 +4619,12 @@
         }
     }
 
+    // One-time initialization, when class is constructed.
+    void init() {
+        mpSymbolLookupFn = 0;
+        mpSymbolLookupContext = 0;
+    }
+
     void clear() {
         tok = 0;
         tokc = 0;
@@ -4673,6 +4685,7 @@
     };
 
     Compiler() {
+        init();
         clear();
     }
 
@@ -4680,6 +4693,11 @@
         cleanup();
     }
 
+    void registerSymbolCallback(ACCSymbolLookupFn pFn, ACCvoid* pContext) {
+        mpSymbolLookupFn = pFn;
+        mpSymbolLookupContext = pContext;
+    }
+
     int compile(const char* text, size_t textLength) {
         int result;
 
@@ -4848,6 +4866,10 @@
         delete text;
     }
 
+    void registerSymbolCallback(ACCSymbolLookupFn pFn, ACCvoid* pContext) {
+        compiler.registerSymbolCallback(pFn, pContext);
+    }
+
     void setError(ACCenum error) {
         if (accError == ACC_NO_ERROR && error != ACC_NO_ERROR) {
             accError = error;
@@ -4883,6 +4905,12 @@
 }
 
 extern "C"
+void accRegisterSymbolCallback(ACCscript* script, ACCSymbolLookupFn pFn,
+                               ACCvoid* pContext) {
+    script->registerSymbolCallback(pFn, pContext);
+}
+
+extern "C"
 void accScriptSource(ACCscript* script,
     ACCsizei count,
     const ACCchar ** string,