Make tree node handle names visible in context user fields

spec/test_context_field_handle.c

@@ -0,0 +1,39 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+#include "testutils.h"
+
+int main()
+{
+    char input[128];
+    size_t i;
+    p_context_t * context;
+    Token token;
+
+    /* Enough tokens that the tree node arena is reallocated during the parse. */
+    memset(input, 0, sizeof(input));
+    for (i = 0u; i < 40u; i++)
+    {
+        input[i] = 'a';
+    }
+
+    context = p_context_new((uint8_t const *)input, strlen(input));
+    assert_eq(P_SUCCESS, p_parse(context));
+
+    /* The handle was stored in a context user field during the parse, before
+     * the remaining nodes were created. It still refers to the same node. */
+    assert_eq(1u, context->have_first);
+    assert(p_node_valid(context->first_item));
+    token = p_Item_pToken1(context->first_item);
+    assert(p_node_valid(token));
+    assert_eq(TOKEN_a, p_Token_token(token));
+    assert_eq(7u, p_Token_pvalue(token));
+
+    /* The stored handle refers to the first Item, which starts at column 1. */
+    assert_eq(1u, p_node_position(context->first_item).row);
+    assert_eq(1u, p_node_position(context->first_item).col);
+
+    p_context_delete(context);
+
+    return 0;
+}