1 files changed, 89 insertions, 0 deletions
diff --git a/semantics.c b/semantics.c
new file mode 100644
index 0000000..865ae2a
--- /dev/null
+++ b/semantics.c
@@ -0,0 +1,89 @@
+#include <stdlib.h>
+#include <string.h>
+#include "semantics.h"
+#define NEW(type) ((type *)malloc(sizeof(type)))
+
+CTable_t ctable_create(Cmp_t cmp, Hashfunc_t hfunc) {
+    CTable_t ct = NEW(CTable);
+    memset(ct->head, 0, sizeof(CTNode*) * MAX_TABLE_SIZE);
+    ct->cmp = cmp;
+    ct->hfunc = hfunc;
+    return ct;
+}
+
+void *ctable_lookup(CTable_t ct, char *key) {
+    unsigned int hv = (ct->hfunc(key)) % MAX_TABLE_SIZE;
+    CTNode *p = ct->head[hv];
+    for (; p; p = p->next)
+        if (ct->cmp(p->key, key))
+            return p->val;
+    return NULL; /* not found */
+}
+
+void ctable_insert(CTable_t ct, char *key, void *val, int lvl) {
+    unsigned int hv = (ct->hfunc(key)) % MAX_TABLE_SIZE;
+    CTNode *np = NEW(CTNode);
+    np->key = key;
+    np->val = val;
+    np->lvl = lvl;
+    np->next = ct->head[hv];
+    ct->head[hv] = np;
+}
+
+void ctable_clip(CTable_t ct, unsigned int hv, int max_lvl) {
+    CTNode *p = ct->head[hv], *np;
+    for (; p && p->lvl > max_lvl; p = np)
+    {
+        np = p->next;
+        free(p);
+    }
+    ct->head[hv] = p;
+}
+
+CScope_t cscope_create() {
+    CScope_t p = NEW(CScope);
+    p->lvl = 0;
+    p->top = NULL;
+    p->tvar = ctable_create(var_cmp, var_hfunc);
+    p->ttype = ctable_create(type_cmp, type_hfunc);
+}
+
+void cscope_push_var(CScope_t cs, CVar *var) {
+    var->next = cs->top->vhead;
+    cs->top->vhead = var;
+    ctable_insert(cs->tvar, var->name, var, cs->lvl);
+}
+
+void cscope_push_type(CScope_t cs, CType *type) {
+    type->next = cs->top->thead;
+    cs->top->thead = type;
+    ctable_insert(cs->ttype, type->name, type, cs->lvl);
+}
+
+void cscope_enter(CScope_t cs) {
+    CSNode *np = NEW(CSNode);
+    np->next = cs->top;
+    cs->top = np;
+    cs->lvl++;
+}
+
+void cscope_exit(CScope_t cs) {
+    CSNode *lower = cs->top->next;
+    CVar *vp;
+    CType *tp;
+    for (vp = cs->top->vhead; vp; vp = vp->next)
+        ctable_clip(cs->tvar, var_hfunc(vp->name), cs->lvl);
+    for (tp = cs->top->thead; tp; tp = tp->next)
+        ctable_clip(cs->ttype, type_hfunc(tp->name), cs->lvl);
+    free(cs->top);
+    cs->top = lower;
+    cs->lvl--;
+}
+
+CVar *cscope_lookup_var(CScope_t cs, char *name) {
+    return ctable_lookup(cs->tvar, name);
+}
+
+CType *cscope_lookup_type(CScope_t cs, char *name) {
+    return ctable_lookup(cs->ttype, name);
+}