simplify parser

Author: voschezang

SHELL_REFERENCE.md

@@ -219,3 +219,36 @@ a *b = list_natural_numbers
 # pure functions can be executed in parallel, using a thread pool
 range 10 >>= math 10 * $ + 1 |> reduce sum
 ```
+
+### Queries
+
+#### Show tabular data
+
+*"Show the users"*
+
+```diff
+- SELECT * FROM users
++ show users
+|      | email              | name   |
+|-----:|:-------------------|:-------|
+| 1000 | name.0@company.com | name_0 |
+| 1001 | name.1@company.com | name_1 |
+| 1002 | name.2@company.com | name_2 |
+```
+
+#### Inner join
+
+*"Find users that own a at least one document"*
+
+```diff
+- SELECT name FROM users INNER JOIN documents ON users.id == document.owner
++ {users | users.id in {documents.owner}} >>= show $1.name
+```
+
+*"Show documents of each user"*
+
+```diff
+- SELECT users.name, documents.name FROM users LEFT JOIN documents ON users.id == document.owner
++ { users documents | users.id = documents.owner } >>= show $1.email $2.name
+```
+

src/mash/shell/grammer/parser.py

@@ -18,7 +18,6 @@
 
 """
 from logging import getLogger
-import logging
 import ply.yacc as yacc
 from mash.shell.ast import Assign, BashPipe, BinaryExpression, Else, ElseIf, ElseIfThen, FunctionDefinition, If, IfThen, IfThenElse, Indent, InlineFunctionDefinition, Lines, LogicExpression, Map, Math, Method, Pipe, Quoted, Return, Shell, Terms, Then, Variable, Word
 from mash.shell.grammer.tokenizer import main, tokens
@@ -29,8 +28,8 @@
 
 
 def parse(text, init=True):
-    # TODO use Node/Tree classes rather than tuples
-    # e.g. classes with a .run() method (extends Runnable<>)
+    """Implement ply methods
+    """
 
     precedence = (
         ('left', 'BREAK'),
@@ -210,7 +209,9 @@ def p_expression_full_conditional(p):
         p[0] = p[1]
 
     def p_expression(p):
-        'expression : basic_expression'
+        """expression : join
+                            | logic_expression
+        """
         p[0] = p[1]
 
     def p_shell(p):
@@ -225,13 +226,6 @@ def p_math(p):
         'expression : MATH expression'
         p[0] = Math(p[2])
 
-    def p_basic_expression(p):
-        """basic_expression : join
-                            | logic_expression
-                            | terms
-        """
-        p[0] = p[1]
-
     def p_logic_binary(p):
         """join : logic_expression AND join
                 | logic_expression AND logic_expression
@@ -342,12 +336,11 @@ def p_error(p):
         tokenizer = main()
     else:
         tokenizer.clone()
-    
+
     log = getLogger()
     parser = yacc.yacc(debug=log)
     if not isinstance(text, str):
-        text
-        raise
+        raise ValueError(text)
 
     # insert a newline to allow empty strings to be matched
     return parser.parse('\n' + text)