This directory contains the jjt grammar for parsing Spanner DDL.
The file DdlParser.head is the header for the combined jjt file containing the
Java parser code.
The remaining ddl_*.jjt files come from the cloud-spanner-emulator:
https://github.com/GoogleCloudPlatform/cloud-spanner-emulator/tree/master/backend/schema/parser
except for ddl_keywords.jjt which is generated during emulator compile time
from ZetaSQL.
Updating DDL grammar requires copying the updated .jjt files from the
emulator, regenerating the ddl_keywords.jjt using the emulator and copying
that as well, and then updating the AST*.java files to handle parsing the
updated grammar.
Note that the file ddl_string_bytes_tokens.jjt should not have the lines
that call ValidateBytesLiteral() and ValidateStringBytesLiteral()
# Build ddl_keywords.jjt
sudo apt install bazel-5.4.0
git clone https://github.com/GoogleCloudPlatform/cloud-spanner-emulator.git
cd cloud-spanner-emulator
bazel build backend/schema/parser:ddl_keywords_jjt
# generated file in bazel-bin/backend/schema/parser/ddl_keywords.jjt
# Compare JJT files
diff bazel-bin/backend/schema/parser/ddl_keywords.jjt ../spanner-schema-diff-tool/src/main/jjtree-sources/ddl_keywords.jjt
diff backend/schema/parser/ddl_expression.jjt ../spanner-schema-diff-tool/src/main/jjtree-sources/ddl_expression.jjt
diff backend/schema/parser/ddl_parser.jjt ../spanner-schema-diff-tool/src/main/jjtree-sources/ddl_parser.jjt
diff backend/schema/parser/ddl_string_bytes_tokens.jjt ../spanner-schema-diff-tool/src/main/jjtree-sources/ddl_string_bytes_tokens.jjt
diff backend/schema/parser/ddl_whitespace.jjt ../spanner-schema-diff-tool/src/main/jjtree-sources/ddl_whitespace.jjt