xo-expression2/xo-tokenizer/docs/examples.rst

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.. _examples:
.. toctree::
:maxdepth: 2
Examples
========
See ``xo-tokenizer/examples/tokenrepl`` for (slighly elaborated) version of code below
.. code-block:: cpp
:linenos:
#include "xo/tokenizer/tokenizer.hpp"
int
main() {
using namespace xo::scm;
using namespace std;
using tokenizer_type = tokenizer<char>;
using span_type = tokenizer_type::span_type;
tokenizer_type tkz;
string input_str;
while (getline(cin, input_str)) {
// we want tokenizer to see newline, it's syntax
input_str.push_back('\n');
span_type input(input_str.begin(), input_str.end());
// input may contain multiple tokens
while (!input.empty()) {
auto [tk, consumed, error] = tkz.scan(input);
if (tk.is_valid()) {
cout << tk;
}
input = input.after_prefix(consumed.size());
}
}
auto [tk, consumed, error] = tkz.notify_eof(spxn_type::from_string(input_str));
if (tk.is_valid()) {
cout << tk;
} else if (error.is_error()) {
cout << "parsing error: " << endl;
error.report(cout);
}
}
Reminder: enable building examples with ``cmake -DXO_ENABLE_EXAMPLES=1 ..``
.. code-block::
:linenos:
$ .build/xo-tokenizer/example/tokenrepl/xo_tokenizer_repl
> 123
<token :type tk_i64 :text 123>
> 123e5
<token :type tk_f64 :text 123e5>
> def sq(x: i64) -> i64 { x * x }
<token :type tk_def :text "">
<token :type tk_symbol :text sq>
<token :type tk_leftparen :text "">
<token :type tk_symbol :text x>
<token :type tk_colon :text "">
<token :type tk_symbol :text i64>
<token :type tk_rightparen :text "">
<token :type tk_yields :text "">
<token :type tk_symbol :text i64>
<token :type tk_leftbrace :text "">
<token :type tk_symbol :text x>
<token :type tk_star :text "">
<token :type tk_symbol :text x>
<token :type tk_rightbrace :text "">
Example of error reporting (via ``error.report(cout)`` above)
.. code-block::
:linenos:
$ .build/xo-tokenizer/example/tokenrepl/xo_tokenizer_repl
> 123q
parsing error:
char: 4
input: 123q
---^
unexpected character in numeric constant
> (8 * 8 * 123fd)
parsing error:
char: 13
input: (8 * 8 * 123fd)
---^
unexpected character in numeric constant