Siarhiej Kresik

.travis.yml

@@ -9,4 +9,8 @@ script:
   - nosetests --cover-branches --with-coverage .
   - pycodestyle --max-line-length=120 .
   - python ./../pycalc_checker.py
+  - cd -
+  # added
+  - cd final_task
+  - python -m unittest
   - cd -

README.md

@@ -0,0 +1,135 @@
+# pycalc
+
+[![Build Status](https://travis-ci.org/siarhiejkresik/Epam-2019-Python-Homework.svg?branch=master)](https://travis-ci.org/siarhiejkresik/Epam-2019-Python-Homework)  
+Python Programming Language Foundation Hometask (EPAM, 2019).
+For task description see [link](https://github.com/siarhiejkresik/Epam-2019-Python-Homework/tree/master/final_task).
+
+`pycalc` is a command-line calculator implemented in pure Python 3 using Top Down Operator Precedence parsing algorithm (Pratt parser). It receives mathematical expression string as an argument and prints evaluated result.
+
+## Features
+
+`pycalc` supports:
+
+- arithmetic operations (`+`, `-`, `*`, `/`, `//`, `%`, `^` (`^` is a power));
+- comparison operations (`<`, `<=`, `==`, `!=`, `>=`, `>`);
+- 2 built-in python functions: `abs` and `round`;
+- all functions and constants from standard python module `math` (trigonometry, logarithms, etc.);
+- functions and constants from the modules provided with `-m` or `--use-modules` command-line option;
+- exit with non-zero exit code on errors.
+
+## How to install
+
+1. `git clone <repository_url>`
+2. `cd <repository_name>/final_task/`
+3. `pip3 install --user .` or `sudo -H pip3 install .`
+
+## Examples
+
+### Command line interface:
+
+```shell
+$ pycalc --help
+usage: pycalc [-h] EXPRESSION [-m MODULE [MODULE ...]]
+
+Pure-python command-line calculator.
+
+positional arguments:
+  EXPRESSION            expression string to evaluate
+
+optional arguments:
+  -h, --help            show this help message and exit
+  -m MODULE [MODULE ...], --use-modules MODULE [MODULE ...]
+                        additional modules to use
+```
+
+### Calculation:
+
+```shell
+$ pycalc '2+2*2'
+6
+
+$ pycalc '2+sin(pi)^(2-cos(e))'
+2.0
+```
+
+```shell
+$ pycalc '5+3<=1'
+False
+```
+
+```shell
+$ pycalc 'e + pi + tau'
+12.143059789228424
+
+$ pycalc '1 + inf'
+inf
+
+$ pycalc '1 - inf'
+-inf
+
+$ pycalc 'inf - inf'
+nan
+
+$ pycalc 'nan == nan'
+False
+```
+
+### Errors:
+
+```shell
+$ pycalc '15*(25+1'
+ERROR: syntax error
+15*(25+1
+        ^
+$ pycalc 'func'
+ERROR: syntax error
+func
+^
+$ pycalc '10 + 1/0 -3'
+ERROR: division by zero
+10 + 1/0 -3
+      ^
+$ pycalc '1 + sin(1,2) - 2'
+ERROR: sin() takes exactly one argument (2 given)
+1 + sin(1,2) - 2
+    ^
+$ pycalc '10^10^10'
+ERROR: math range error
+10^10^10
+  ^
+$ pycalc  '(-1)^0.5'
+ERROR: math domain error
+(-1)^0.5
+    ^
+$ pycalc ''
+ERROR: empty expression provided
+
+$ pycalc '1514' -m fake calendar nonexistent time
+ERROR: no module(s) named fake, nonexistent
+```
+
+### Additional modules:
+
+```python
+# my_module.py
+def sin(number):
+    return 42
+```
+
+```shell
+$ pycalc 'sin(pi/2)'
+1.0
+$ pycalc 'sin(pi/2)' -m my_module
+42
+$ pycalc 'THURSDAY' -m calendar
+3
+$ pycalc 'sin(pi/2) - THURSDAY * 10' -m my_module calendar
+12
+```
+
+## References
+
+- https://en.wikipedia.org/wiki/Pratt_parser
+- https://tdop.github.io/
+- http://www.oilshell.org/blog/2017/03/31.html
+- https://engineering.desmos.com/articles/pratt-parser

final_task/Makefile

@@ -0,0 +1,34 @@
+.DEFAULT_GOAL := run
+
+PROGRAMM_NAME := pycalc
+SRC_FOLDER := $(PROGRAMM_NAME)
+INSTALLED_EXECUTABLE_DIR := ~/.local/bin
+
+PYTHON := python3
+
+PIP := pip3
+PIP_LOCAL := --user
+
+run:
+	$(INSTALLED_EXECUTABLE_DIR)/$(PROGRAMM_NAME)
+
+run-source:
+	$(PYTHON) -m $(SRC_FOLDER)
+
+install:
+	@echo "Installing..."
+	$(PIP) install $(PIP_LOCAL) .
+
+install-dev:
+	@echo "Installing in the development mode..."
+	$(PIP) install $(PIP_LOCAL) --editable .
+
+uninstall:
+	@echo "Uninstalling..."
+	$(PIP) uninstall $(PROGRAMM_NAME) -y
+
+show:
+	$(PIP) show $(PROGRAMM_NAME)
+
+pycodestyle:
+	pycodestyle $(PROGRAMM_NAME)/*

final_task/pycalc/__init__.py

@@ -0,0 +1,6 @@
+"""
+Pure-python implementation of a command-line calculator.
+
+Receives mathematical expression string as an argument
+and prints evaluated result.
+"""

final_task/pycalc/__main__.py

@@ -0,0 +1,18 @@
+"""
+Pure-python implementation of a command-line calculator.
+
+Receives mathematical expression string as an argument
+and prints evaluated result.
+"""
+
+from pycalc.cli import Cli
+
+
+def main():
+    """Pure-python implementation of a command-line calculator."""
+
+    Cli().run()
+
+
+if __name__ == "__main__":
+    main()

final_task/pycalc/args.py

@@ -0,0 +1,47 @@
+"""
+Parse command-line options.
+"""
+
+import argparse
+
+PARSER = {
+    'description': 'Pure-python command-line calculator.'
+}
+
+EXPRESSION = {
+    'name_or_flags': ['expression'],
+    'keyword_arguments': {
+        'metavar': 'EXPRESSION',
+        'type': str,
+        'help': 'expression string to evaluate'
+    }
+}
+
+MODULE = {
+    'name_or_flags': ['-m', '--use-modules'],
+    'keyword_arguments': {
+        'metavar': 'MODULE',
+        'type': str,
+        'nargs': '+',
+        'help': 'additional modules to use',
+        'dest': 'modules'
+    }
+}
+
+ARGUMENTS = (
+    EXPRESSION,
+    MODULE,
+)
+
+
+def get_args():
+    """Parse command line arguments."""
+
+    parser = argparse.ArgumentParser(**PARSER)
+
+    for arg in ARGUMENTS:
+        parser.add_argument(*arg['name_or_flags'], **arg['keyword_arguments'])
+
+    args = parser.parse_args()
+
+    return args

final_task/pycalc/calculator/__init__.py

@@ -0,0 +1,10 @@
+"""
+The calculator package.
+"""
+
+from .calculator import calculator
+from .errors import (
+    CalculatorError,
+    CalculatorInitializationError,
+    CalculatorCalculationError
+)

final_task/pycalc/calculator/calculator.py

@@ -0,0 +1,102 @@
+"""
+Initialization of a calculator. Return a calculator instance.
+"""
+
+from pycalc.lexer import Lexer
+from pycalc.parser import Parser, ParserGenericError
+from pycalc.importer import ModuleImportErrors
+
+from .formatters import err_msg_with_ctx_formatter, err_modules_import_formatter
+from .errors import CalculatorCalculationError, CalculatorInitializationError, get_err_msg
+from .importer import build_modules_registry
+from .matchers import build_matchers
+from .messages import (
+    CALCULATOR_INITIALIZATION_ERROR,
+    CANT_PARSE_EXPRESSION,
+    EMPTY_EXPRESSION_PROVIDED,
+)
+from .precedence import Precedence
+from .specification import build_specification
+
+
+class Calculator:
+    """
+    The calculator class.
+
+    Provide a method to calculate an expression from a string.
+    """
+
+    def __init__(self, parser):
+        self._parser = parser
+
+    def calculate(self, expression):
+        """
+        Calculate an expression.
+
+        Return result of calculation or raise a `CalculatorCalculationError` exception
+        if calculation fails.
+        """
+
+        # empty expression
+        if not expression:
+            raise CalculatorCalculationError(EMPTY_EXPRESSION_PROVIDED)
+
+        # calculate an expression
+        try:
+            result = self._parser.parse(expression)
+            return result
+
+        # handle calculation errors
+        except ParserGenericError as exc_wrapper:
+
+            # ’unwrap’ an original exception and get context
+            exc = exc_wrapper.__cause__
+            ctx = exc.ctx if hasattr(exc, 'ctx') else exc_wrapper.ctx
+
+            # an error message
+            err_msg = get_err_msg(exc)
+            err_msg = err_msg_with_ctx_formatter(err_msg, ctx)
+
+        # handle all other errors
+        except Exception as exc:
+            err_msg = CANT_PARSE_EXPRESSION
+
+        raise CalculatorCalculationError(err_msg)
+
+
+def calculator(modules_names=None):
+    """
+    Initialize a calculator and return a Calculator instance.
+
+    Raise a `CalculatorInitializationError` exception when initialization fails."""
+
+    try:
+        # import constants and functions from default and requested modules
+        modules_registry = build_modules_registry(modules_names)
+
+        # build lexemes matchers
+        matchers = build_matchers(modules_registry)
+
+        # create a lexer
+        lexer = Lexer(matchers)
+
+        # build a specification for a parser
+        spec = build_specification(modules_registry)
+
+        # create a parser
+        power = Precedence.DEFAULT
+        parser = Parser(spec, lexer, power)
+
+        # create a calculator
+        calculator_ = Calculator(parser)
+
+        return calculator_
+
+    except ModuleImportErrors as exc:
+        modules_names = exc.modules_names
+        err_msg = err_modules_import_formatter(modules_names)
+
+    except Exception:
+        err_msg = CALCULATOR_INITIALIZATION_ERROR
+
+    raise CalculatorInitializationError(err_msg)