how do I do nesting...

resources/scripts/scratch

@@ -1,5 +1,7 @@
 # this is a comment
 elem table {
+    elem tr {
 
+    }
 }
 

src/parser/parser.rs

@@ -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::combinator::{cut, map, map_res, opt, value, verify, map_opt};
-use nom::error::ParseError;
+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, &
 }
 
 
-
+// Eat up whitespace characters
-/// 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
 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())));
 }