Simple Expressions

A small expression language with variables, function calls, simple types and common operators

• Literals
  • Integers: sequence of digits, optionally with a leading '-'.
  • Floats: digits with a decimal point, optionally with a leading '-'.
  • Strings: delimited by single ' or double " quotes. Supported escapes: \n, \r, \t, \, ", \'. Newlines are not allowed inside strings unless escaped as a backslash followed by a newline.
  • Booleans: true, false.
• Whitespace and comments
  • Any spaces, tabs, or newlines are ignored.
  • Line comments start with // and continue to the end of the line.
• Grouping
  • Parentheses ( ... ) group sub-expressions.
• Identifiers, variables and functions
  • Identifiers follow the usual rules: start with a letter or underscore, then letters, digits, or underscores.
  • Dotted paths are supported to reference nested names: a.b.c.
  • An identifier may be followed by a function call with parentheses and parameters: ns.func(arg1, arg2).
• Operators
  • Arithmetic: +, -, *, /, %, ^
  • Comparisons: <, <=, >, >=, ==, !=
  • Logical: &&, ||, and unary !
• String interpolation (library API)
  • When using the provided Evaluator, the helper evaluate_interpolated replaces ${ ... } segments with the value of the contained expression. The result is always a string.