Add p_parse_inner_XXX() APIs

spec/test_parse_inner_shared.d

@@ -0,0 +1,56 @@
+import testparser;
+import std.stdio;
+import testutils;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    /* See test_parse_inner_shared.c for details on the grammar. */
+
+    /* Sanity-check that parse_Start resolves R1 vs R2 via lookahead. */
+    string input = "aba";
+    p_context_t * context = p_context_new(input);
+    assert(p_parse_Start(context) == P_SUCCESS);
+
+    input = "abb";
+    context = p_context_new(input);
+    assert(p_parse_Start(context) == P_SUCCESS);
+
+    /* Standard parse of R1 succeeds on "ab". */
+    input = "ab";
+    context = p_context_new(input);
+    assert(p_parse_R1(context) == P_SUCCESS);
+    assert(p_result_R1(context) == 11);
+
+    /* Standard parse of R1 fails on "abb". */
+    input = "abb";
+    context = p_context_new(input);
+    assert(p_parse_R1(context) == P_UNEXPECTED_TOKEN);
+
+    /* parse_inner_R1("abb", [b]) succeeds: `b` is the lookahead that
+     * parse_Start would use to select R2 over R1, but from R1's own start
+     * state R1 reduces unconditionally, and the follow-token shift retry at
+     * the R1-accepting state completes the parse. */
+    input = "abb";
+    context = p_context_new(input);
+    p_token_t[] follow_tokens_b = [TOKEN_b];
+    assert(p_parse_inner_R1(context, follow_tokens_b) == P_SUCCESS);
+    assert(p_result_R1(context) == 11);
+
+    /* parse_inner_R1("aba", [a]) also succeeds. */
+    input = "aba";
+    context = p_context_new(input);
+    p_token_t[] follow_tokens_a = [TOKEN_a];
+    assert(p_parse_inner_R1(context, follow_tokens_a) == P_SUCCESS);
+    assert(p_result_R1(context) == 11);
+
+    /* parse_inner_R1("ab", null) behaves like p_parse_R1("ab"). */
+    input = "ab";
+    context = p_context_new(input);
+    assert(p_parse_inner_R1(context, null) == P_SUCCESS);
+    assert(p_result_R1(context) == 11);
+}