switch expression - add compile errors

   * for duplicate integer value
   * for missing integer values
   * for missing else prong

see #43

1 files changed, 81 insertions, 0 deletions

diff --git a/src/range_set.cpp b/src/range_set.cpp
new file mode 100644
index 0000000000..6158f52a00
--- /dev/null
+++ b/src/range_set.cpp
@@ -0,0 +1,81 @@
+#include "range_set.hpp"
+
+AstNode *rangeset_add_range(RangeSet *rs, BigNum *first, BigNum *last, AstNode *source_node) {
+    for (size_t i = 0; i < rs->src_range_list.length; i += 1) {
+        RangeWithSrc *range_with_src = &rs->src_range_list.at(i);
+        Range *range = &range_with_src->range;
+        if ((bignum_cmp_gte(first, &range->first) && bignum_cmp_lte(first, &range->last)) ||
+            (bignum_cmp_gte(last, &range->first) && bignum_cmp_lte(last, &range->last)))
+        {
+            return range_with_src->source_node;
+        }
+    }
+    rs->src_range_list.append({{*first, *last}, source_node});
+
+    return nullptr;
+
+}
+
+static bool add_range(ZigList<Range> *list, Range *new_range, BigNum *one) {
+    for (size_t i = 0; i < list->length; i += 1) {
+        Range *range = &list->at(i);
+
+        BigNum first_minus_one;
+        if (bignum_sub(&first_minus_one, &range->first, one))
+            zig_unreachable();
+
+        if (bignum_cmp_eq(&new_range->last, &first_minus_one)) {
+            range->first = new_range->first;
+            return true;
+        }
+
+        BigNum last_plus_one;
+        if (bignum_add(&last_plus_one, &range->last, one))
+            zig_unreachable();
+
+        if (bignum_cmp_eq(&new_range->first, &last_plus_one)) {
+            range->last = new_range->last;
+            return true;
+        }
+    }
+    list->append({new_range->first, new_range->last});
+    return false;
+}
+
+bool rangeset_spans(RangeSet *rs, BigNum *first, BigNum *last) {
+    ZigList<Range> cur_list_value = {0};
+    ZigList<Range> other_list_value = {0};
+    ZigList<Range> *cur_list = &cur_list_value;
+    ZigList<Range> *other_list = &other_list_value;
+
+    for (size_t i = 0; i < rs->src_range_list.length; i += 1) {
+        RangeWithSrc *range_with_src = &rs->src_range_list.at(i);
+        Range *range = &range_with_src->range;
+        cur_list->append({range->first, range->last});
+    }
+
+    BigNum one;
+    bignum_init_unsigned(&one, 1);
+
+    bool changes_made = true;
+    while (changes_made) {
+        changes_made = false;
+        for (size_t cur_i = 0; cur_i < cur_list->length; cur_i += 1) {
+            Range *range = &cur_list->at(cur_i);
+            changes_made = add_range(other_list, range, &one) || changes_made;
+        }
+        ZigList<Range> *tmp = cur_list;
+        cur_list = other_list;
+        other_list = tmp;
+        other_list->resize(0);
+    }
+
+    if (cur_list->length != 1)
+        return false;
+    Range *range = &cur_list->at(0);
+    if (bignum_cmp_neq(&range->first, first))
+        return false;
+    if (bignum_cmp_neq(&range->last, last))
+        return false;
+    return true;
+}