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how do I do nesting...

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mitchellhansen
2020-10-12 23:01:22 -07:00
parent 32ae95b3d0
commit 8ceb805a52
2 changed files with 130 additions and 31 deletions
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2
resources/scripts/scratch
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@@ -1,5 +1,7 @@
# this is a comment
elem table {
elem tr {
}
}

159
src/parser/parser.rs
View File

@@ -1,13 +1,13 @@
use nom::branch::alt;
use nom::bytes::complete::{escaped, is_not, take, take_till, take_until, take_while};
use nom::bytes::complete::{tag, take_while1, take_while_m_n};
use nom::character::complete::{anychar, char, line_ending, newline, not_line_ending, one_of};
use nom::character::complete::{anychar, char, line_ending, newline, not_line_ending, one_of, multispace1};
use nom::character::complete::alphanumeric1 as alphanumeric;
use nom::character::is_alphabetic;
use nom::combinator::{cut, map, map_res, opt};
use nom::error::ParseError;
use nom::combinator::{cut, map, map_res, opt, value, verify, map_opt};
use nom::error::{ParseError, FromExternalError};
use nom::IResult;
use nom::multi::many0;
use nom::multi::{many0, fold_many0};
use nom::number::complete::be_u16;
use nom::sequence::{delimited, preceded, terminated, tuple};
@@ -63,7 +63,7 @@ pub fn elem<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &'a
let (input, _) = delimited(opt(sp), tag("elem"), sp)(input)?;
let (input, elem_name) = parse_str(input)?;
let (input, elem_name) = parse_token(input)?;
let (input, _) = scope::<'a, E>(input)?;
@@ -73,11 +73,132 @@ pub fn elem<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &'a
}
fn parse_str<'a, E: ParseError<&'a str>>(i: &'a str) -> IResult<&'a str, &'a str, E> {
// Parse a single alphanumeric token delimited by spaces
fn parse_token<'a, E: ParseError<&'a str>>(i: &'a str) -> IResult<&'a str, &'a str, E> {
let chars = "\n";
escaped(alphanumeric, '\\', one_of(""))(i)
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum StringFragment<'a> {
Literal(&'a str),
EscapedChar(char),
EscapedWS,
}
fn parse_unicode<'a, E: ParseError<&'a str> + FromExternalError<&'a str, std::num::ParseIntError>>(input: &'a str)
-> IResult<&'a str, char, E> {
// `take_while_m_n` parses between `m` and `n` bytes (inclusive) that match
// a predicate. `parse_hex` here parses between 1 and 6 hexadecimal numerals.
let parse_hex = take_while_m_n(1, 6, |c: char| c.is_ascii_hexdigit());
// `preceeded` takes a prefix parser, and if it succeeds, returns the result
// of the body parser. In this case, it parses u{XXXX}.
let parse_delimited_hex = preceded(
char('u'),
// `delimited` is like `preceded`, but it parses both a prefix and a suffix.
// It returns the result of the middle parser. In this case, it parses
// {XXXX}, where XXXX is 1 to 6 hex numerals, and returns XXXX
delimited(char('{'), parse_hex, char('}')),
);
// `map_res` takes the result of a parser and applies a function that returns
// a Result. In this case we take the hex bytes from parse_hex and attempt to
// convert them to a u32.
let parse_u32 = map_res(parse_delimited_hex, move |hex| u32::from_str_radix(hex, 16));
// map_opt is like map_res, but it takes an Option instead of a Result. If
// the function returns None, map_opt returns an error. In this case, because
// not all u32 values are valid unicode code points, we have to fallibly
// convert to char with from_u32.
map_opt(parse_u32, |value| std::char::from_u32(value))(input)
}
/// Parse an escaped character: \n, \t, \r, \u{00AC}, etc.
fn parse_escaped_char<'a, E: ParseError<&'a str>+ FromExternalError<&'a str, std::num::ParseIntError>>(input: &'a str)
-> IResult<&'a str, char, E> {
preceded(
char('\\'),
// `alt` tries each parser in sequence, returning the result of
// the first successful match
alt((
parse_unicode,
// The `value` parser returns a fixed value (the first argument) if its
// parser (the second argument) succeeds. In these cases, it looks for
// the marker characters (n, r, t, etc) and returns the matching
// character (\n, \r, \t, etc).
value('\n', char('n')),
value('\r', char('r')),
value('\t', char('t')),
value('\u{08}', char('b')),
value('\u{0C}', char('f')),
value('\\', char('\\')),
value('/', char('/')),
value('"', char('"')),
)),
)(input)
}
/// Parse a backslash, followed by any amount of whitespace. This is used later
/// to discard any escaped whitespace.
fn parse_escaped_whitespace<'a, E: ParseError<&'a str>>(
input: &'a str,
) -> IResult<&'a str, &'a str, E> {
preceded(char('\\'), multispace1)(input)
}
/// Parse a non-empty block of text that doesn't include \ or "
fn parse_literal<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &'a str, E> {
// `is_not` parses a string of 0 or more characters that aren't one of the
// given characters.
let not_quote_slash = is_not("\"\\");
// `verify` runs a parser, then runs a verification function on the output of
// the parser. The verification function accepts out output only if it
// returns true. In this case, we want to ensure that the output of is_not
// is non-empty.
verify(not_quote_slash, |s: &str| !s.is_empty())(input)
}
/// Combine parse_literal, parse_escaped_whitespace, and parse_escaped_char
/// into a StringFragment.
fn parse_fragment<'a, E: ParseError<&'a str>+ FromExternalError<&'a str, std::num::ParseIntError>>(
input: &'a str,
) -> IResult<&'a str, StringFragment<'a>, E> {
alt((
// The `map` combinator runs a parser, then applies a function to the output
// of that parser.
map(parse_literal, StringFragment::Literal),
map(parse_escaped_char, StringFragment::EscapedChar),
value(StringFragment::EscapedWS, parse_escaped_whitespace),
))(input)
}
/// Parse a string. Use a loop of parse_fragment and push all of the fragments
/// into an output string.
fn parse_string<'a, E: ParseError<&'a str> + FromExternalError<&'a str, std::num::ParseIntError>>(input: &'a str) -> IResult<&'a str, String, E> {
// fold_many0 is the equivalent of iterator::fold. It runs a parser in a loop,
// and for each output value, calls a folding function on each output value.
let build_string = fold_many0(
// Our parser function– parses a single string fragment
parse_fragment,
// Our init value, an empty string
String::new(),
// Our folding function. For each fragment, append the fragment to the
// string.
|mut string, fragment| {
match fragment {
StringFragment::Literal(s) => string.push_str(s),
StringFragment::EscapedChar(c) => string.push(c),
StringFragment::EscapedWS => {}
}
string
},
);
delimited(char('"'), build_string, char('"'))(input)
}
// Parse from a # to a newline character
pub fn comment<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &'a str, E> {
@@ -94,21 +215,14 @@ pub fn comment<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, &
}
/// parser combinators are constructed from the bottom up:
/// first we write parsers for the smallest elements (here a space character),
/// then we'll combine them in larger parsers
// Eat up whitespace characters
fn sp<'a>(i: &'a str) -> IResult<&'a str, &'a str> {
let chars = " \t\r\n";
// nom combinators like `take_while` return a function. That function is the
// parser,to which we can pass the input
take_while(move |c| chars.contains(c))(i)
}
pub fn parse_script<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, ScriptMeta, E> {
println!("Full input string : {:?}\n", input);
let mut remaining_str = input;
@@ -125,23 +239,6 @@ pub fn parse_script<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a s
remaining_str = x.unwrap().0;
}
//println!("{:?}", x);
// if let Ok(v) = elem_tag(input) {
// println!("Found elem tag");
// if let Ok(v) = sp(v.0) {
//
// println!("ate some spaces");
// }
// else {
// println!("didn't eat spaces?");
// }
// }
// if let Ok(v) = comment(input) {
// println!("Found comment tag")
// }
return Ok((remaining_str, ScriptMeta::Comment(String::default())));
}