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plthy_impl/parser.py

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+from rply import ParserGenerator
+
+from plthy_impl.lexer import ALL_TOKENS
+from plthy_impl import ast_nodes
+
+class Parser():
+    def __init__(self):
+        self.pg = ParserGenerator(
+            [i[0] for i in ALL_TOKENS],
+            precedence=[
+                ('left', ["KEYWORD_MAYBE", "KEYWORD_RETURN"]),
+                ('left', ["KEYWORD_IF", "KEYWORD_DEFINE", "KEYWORD_AS"]),
+                ('left', ["KEYWORD_DO", "BUILTIN"]),
+                ('left', ["SYMBOL_EQUALS", "SYMBOL_SET"]),
+                ('left', ["SYMBOL_PLUS", "SYMBOL_MINUS"]),
+                ('left', ["SYMBOL_TIMES", "SYMBOL_DIVIDE"])
+            ]
+        )
+
+    def parse(self, token_input) -> ast_nodes.BaseBox:
+        # Top-level program stuff
+        @self.pg.production('program : KEYWORD_HELLO SYMBOL_PIPE statements KEYWORD_GOODBYE SYMBOL_PIPE')
+        def program(tokens):
+            return ast_nodes.Program(tokens[2])
+
+        ## statements ##
+        @self.pg.production('statements : ')
+        def statements_none(_):
+            return []
+
+        @self.pg.production('statements : statement SYMBOL_PIPE statements')
+        def statements(tokens):
+            return [tokens[0]] + tokens[2]
+
+        ## statement ##
+        @self.pg.production('statement : SYMBOL_DOLLAR expression SYMBOL_SET ID', precedence="SYMBOL_SET")
+        def statement_set(tokens):
+            return ast_nodes.StatementSet(tokens[1], tokens[3].value)
+
+        @self.pg.production('statement : KEYWORD_DO command')
+        def statement_do(tokens):
+            return ast_nodes.Do(tokens[1])
+
+        @self.pg.production('statement : KEYWORD_MAYBE statement')
+        def statement_maybe(tokens):
+            return ast_nodes.Maybe(tokens[1])
+
+        @self.pg.production('statement : statement KEYWORD_IF expression')
+        def statement_if(tokens):
+            return ast_nodes.StatementIf(tokens[0], tokens[2])
+
+        @self.pg.production('statement : KEYWORD_DEFINE ID SYMBOL_LT DATA_NUMERAL SYMBOL_GT KEYWORD_AS statement', precedence="KEYWORD_DEFINE")
+        def statement_define(tokens):
+            return ast_nodes.StatementDefine(tokens[1].value, int(tokens[3].value), tokens[6])
+
+        @self.pg.production('statement : KEYWORD_RETURN expression')
+        def statement_return(tokens):
+            return ast_nodes.StatementReturn(tokens[1])
+
+        @self.pg.production('statement : SYMBOL_LBRACKET statements SYMBOL_RBRACKET')
+        def statement_scope(tokens):
+            return ast_nodes.Scope(tokens[1])
+
+        ## command ##
+        @self.pg.production('command : BUILTIN SYMBOL_LT expressions SYMBOL_GT')
+        def command_builtin(tokens):
+            return ast_nodes.Builtin(tokens[0].value, tokens[2])
+
+        @self.pg.production('command : SYMBOL_QUOTE ID SYMBOL_QUOTE SYMBOL_LT expressions SYMBOL_GT')
+        def command_call(tokens):
+            return ast_nodes.Call(tokens[1].value,tokens[4])
+
+        ## expressions ##
+        @self.pg.production('expressions : ')
+        def expressions_none(_):
+            return []
+
+        @self.pg.production('expressions : expression SYMBOL_SEMICOLON expressions ')
+        def expressions(tokens):
+            return [tokens[0]] + tokens[2]
+
+        ## expression ##
+        @self.pg.production('expression : DATA_NUMERAL')
+        def exp_numeral(tokens):
+            return ast_nodes.ExpNumeral(float(tokens[0].value))
+
+        @self.pg.production('expression : DATA_STRING')
+        def exp_string(tokens):
+            return ast_nodes.ExpString(tokens[0].value[1:-1])
+
+        @self.pg.production('expression : statement', precedence="KEYWORD_IF")
+        def exp_statement(tokens):
+            return(tokens[0])
+
+        @self.pg.production('expression : KEYWORD_VARIABLE ID')
+        def exp_variable(tokens):
+            return ast_nodes.ExpVariable(tokens[1].value)
+
+        @self.pg.production('expression : expression SYMBOL_PLUS expression')
+        @self.pg.production('expression : expression SYMBOL_MINUS expression')
+        @self.pg.production('expression : expression SYMBOL_TIMES expression')
+        @self.pg.production('expression : expression SYMBOL_DIVIDE expression')
+        @self.pg.production('expression : expression SYMBOL_EQUALS expression')
+        def exp_a_binop(tokens):
+            return ast_nodes.ExpABinop(tokens[1].value,tokens[0],tokens[2])
+
+        @self.pg.production('expression : KEYWORD_ARGUMENT ARG')
+        def exp_arg(tokens):
+            return ast_nodes.ExpArg(int(tokens[1].value[1:]))
+
+        ## Error Handling ##
+        @self.pg.error
+        def error_handle(token):
+            raise Exception(token.name, token.value, token.source_pos)
+
+        ## Finish ##
+        parser = self.pg.build()
+        return parser.parse(token_input)