Add deparsing functionality that turns parse tree back into a SQL query

This is based on the deparser that was written over multiple years for
the pg_query Ruby library, and is now accessible for all bindings through
this new API and implementation.

Note that there are still many (mostly special case) queries that are
not yet supported by the deparser.

Makefile

@@ -181,11 +181,12 @@ examples/normalize_error: examples/normalize_error.c $(ARLIB)
 examples/simple_plpgsql: examples/simple_plpgsql.c $(ARLIB)
 	$(CC) $(TEST_CFLAGS) -o $@ -g examples/simple_plpgsql.c $(ARLIB) $(TEST_LDFLAGS)
 
-TESTS = test/complex test/concurrency test/fingerprint test/normalize test/parse test/parse_protobuf test/parse_plpgsql test/scan
+TESTS = test/complex test/concurrency test/deparse test/fingerprint test/normalize test/parse test/parse_protobuf test/parse_plpgsql test/scan
 test: $(TESTS)
 ifeq ($(VALGRIND),1)
 	$(VALGRIND_MEMCHECK) test/complex || (cat test/valgrind.log && false)
 	$(VALGRIND_MEMCHECK) test/concurrency || (cat test/valgrind.log && false)
+	$(VALGRIND_MEMCHECK) test/deparse || (cat test/valgrind.log && false)
 	$(VALGRIND_MEMCHECK) test/fingerprint || (cat test/valgrind.log && false)
 	$(VALGRIND_MEMCHECK) test/normalize || (cat test/valgrind.log && false)
 	$(VALGRIND_MEMCHECK) test/parse || (cat test/valgrind.log && false)
@@ -197,6 +198,7 @@ ifeq ($(VALGRIND),1)
 else
 	test/complex
 	test/concurrency
+	test/deparse
 	test/fingerprint
 	test/normalize
 	test/parse
@@ -214,6 +216,9 @@ test/complex: test/complex.c $(ARLIB)
 test/concurrency: test/concurrency.c test/parse_tests.c $(ARLIB)
 	$(CC) $(TEST_CFLAGS) -o $@ test/concurrency.c $(ARLIB) $(TEST_LDFLAGS)
 
+test/deparse: test/deparse.c test/deparse_tests.c $(ARLIB)
+	$(CC) $(TEST_CFLAGS) -o $@ test/deparse.c $(ARLIB) $(TEST_LDFLAGS)
+
 test/fingerprint: test/fingerprint.c test/fingerprint_tests.c $(ARLIB)
 	# We have "-Isrc/" because this test uses pg_query_fingerprint_with_opts
 	$(CC) $(TEST_CFLAGS) -o $@ -Isrc/ test/fingerprint.c $(ARLIB) $(TEST_LDFLAGS)

pg_query.h

@@ -34,6 +34,11 @@ typedef struct {
   PgQueryError* error;
 } PgQueryProtobufParseResult;
 
+typedef struct {
+  char* query;
+  PgQueryError* error;
+} PgQueryDeparseResult;
+
 typedef struct {
   char* plpgsql_funcs;
   PgQueryError* error;
@@ -62,9 +67,12 @@ PgQueryPlpgsqlParseResult pg_query_parse_plpgsql(const char* input);
 
 PgQueryFingerprintResult pg_query_fingerprint(const char* input);
 
+PgQueryDeparseResult pg_query_deparse_protobuf(PgQueryProtobuf parse_tree);
+
 void pg_query_free_normalize_result(PgQueryNormalizeResult result);
 void pg_query_free_scan_result(PgQueryScanResult result);
 void pg_query_free_parse_result(PgQueryParseResult result);
+void pg_query_free_deparse_result(PgQueryDeparseResult result);
 void pg_query_free_protobuf_parse_result(PgQueryProtobufParseResult result);
 void pg_query_free_plpgsql_parse_result(PgQueryPlpgsqlParseResult result);
 void pg_query_free_fingerprint_result(PgQueryFingerprintResult result);

scripts/extract_source.rb

@@ -531,6 +531,8 @@ def write_out
 runner.deep_resolve('bms_free')
 runner.deep_resolve('makeBitString')
 
+# Needed for deparse
+runner.deep_resolve('pg_toupper')
 
 # Needed for normalize
 runner.deep_resolve('pg_qsort')