Motivation

In a word, I want to build my own script language that can be written in C or a simplied version of C. And here are some basic rules:

• All the code would be written in C++ and C++ only, using c++11 standard. No more than that.
• The code should be able to be built anywhere there is a C++ compiler. so, we will use Makefile to build this project. No cmake or bazel.

Goal

For example, you have a elsh script example.sh like this:

int a = 0;
int b = 10;
do {
  a += 1;
  print(a);
} while ( a < b );

and you have already install the elsh in the system, then you can use:

elsh example.sh

to run this script.

Definitions

Basic Data Types

Name	Common name	Character sequence
Dt_int32	32bit integer	int32
Dt_int64	64bit integer	int64
Dt_uint32	32bit unsigned integer	uint32
Dt_uint64	64bit unsigned integer	uint64
Dt_double	double-precision floating-point number	double
Dt_char	charater	char
Dt_string	string	string
Dt_void	empty type	void
Dt_bool	boolean	bool

Operators

Name	Common name	Character sequence
Op_multiply	multiply	*
Op_divide	divide	/
Op_mod	mod	%
Op_add	plus	+
Op_subtract	minus	-
Op_negate	unary minus	-
Op_less	less than	<
Op_lessequal	less than or equal	<=
Op_greater	greater than	>
Op_greaterequal	greater than or equal	>=
Op_equal	equal	==
Op_notequal	not equal	!=
Op_not	unary not	!
Op_assign	assignment	=
Op_and	logical and	&&
Op_or	logical or	¦¦

Symbols

Name	Common name	Character sequence
LeftParen	left parenthesis	(
RightParen	right parenthesis	)
LeftBrace	left brace	{
RightBrace	right brace	}
LeftBracket	left bracket	[
RightBracket	right bracket	]
Semicolon	semi-colon	;
Comma	comma	,

Reverved Keywords

Name	Character sequence
Keyword_if	if
Keyword_else	else
Keyword_while	while
Keyword_break	break
Keyword_continue	continue
Keyword_do	do
Keyword_for	for
Keyword_print	print
Keyword_putc	putc
Keyword_return	return
Keyword_true	true
Keyword_false	false
Keyword_const	const

Comments

Name	Character sequence
SingleLine Comments	//
MultiLine Comments	/* ... */

Build

make