Represent character sets as sets of character ranges

character_set_spec.cpp

@@ -0,0 +1,51 @@
+#include "spec_helper.h"
+#include "rules.h"
+
+using namespace rules;
+
+START_TEST
+
+describe("character sets", []() {
+    describe("computing the complement", []() {
+        it("works for the set containing only the null character", []() {
+            CharacterSet set1({ '\0' });
+            auto set2 = set1.complement();
+            AssertThat(set2, Equals(CharacterSet({
+                { 1, -1 },
+            }, true)));
+            AssertThat(set2.complement(), Equals(set1));
+        });
+
+        it("works for single character sets", []() {
+            CharacterSet set1({ 'b' });
+            auto set2 = set1.complement();
+            AssertThat(set2, Equals(CharacterSet({
+                { 0, 'a' },
+                { 'c', -1 },
+            })));
+            AssertThat(set2.complement(), Equals(set1));
+        });
+    });
+    
+    describe("computing unions", []() {
+        it("works for disjoint sets", []() {
+            CharacterSet set({ {'a', 'z'} }, true);
+            set.union_with(CharacterSet({ {'A', 'Z'} }, true));
+            AssertThat(set, Equals(CharacterSet({ {'a', 'z'}, {'A', 'Z'}, })));
+        });
+        
+        it("works for sets with adjacent ranges", []() {
+            CharacterSet set({ {'a', 'r'} }, true);
+            set.union_with(CharacterSet({ {'s', 'z'} }, true));
+            AssertThat(set, Equals(CharacterSet({ {'a', 'z'} }, true)));
+        });
+        
+        it("works when the result becomes a continuous range", []() {
+            CharacterSet set({ {'a', 'd'}, {'f', 'z'} }, true);
+            set.union_with(CharacterSet({ {'d', 'f'} }, true));
+            AssertThat(set, Equals(CharacterSet({ {'a', 'z'} }, true)));
+        });
+    });
+});
+
+END_TEST