monasca-analytics/monasca_analytics/banana/grammar/README.md

Grammar

This folder is all about the definition of the banana grammar. The grammar purpose is to convert the input, text, into an abstract syntax tree (AST).

This is the first step of the pipeline:

      +--------+                  +---------+
      |        |                  |         |
      |  Text  | --- grammar ---> |   AST   | --->
      |        |                  |         |
      +--------+                  +---------+

The module ast.py contains all the possible ASTNode which itself is defined in base_ast.py.

Current status

• Parsing connections such as a -> b, a -> [b, c], [a, b] -> [c, d]
• Parsing numbers
• Parsing string literals
• Parsing booleans
• Parsing assignments where the left hand side can be a property or an identifier.
• Parsing assignments where the right hand side is a number, a string literal, a property or an identifier.
• Parsing components arguments using a constructor-like syntax.
• Parsing ingestors generators (for JSON dialect)
• Parsing imports such as from ldp.monasca import *
• Parsing disconnections such as a !-> b (requires imports)

Tests

All test regarding the grammar (i.e. the syntax and the way the AST is built) is defined in test/banana/grammar.

This folder looks like this:

test/banana/grammar
├── should_fail
│   ├── ...
│   └── file.banana
├── should_pass
│   ├── ...
│   └── file.banana
└── test_config.py

The test_config generates one test for each file in the should_pass and should_fail directories.

Test can assert various things using instructions below.

Available instruction

• # RAISE <exception-name>: Check that exception-name is raised.
• # STMT_EQ <ast-of-statements> Check the AST of statements.
• # AST_EQ <full-ast> Check the full AST.
• # CONN_EQ <ast-of-connections> Check the AST of connections.