spdl 0.0.1

/*!
This crate contains an API to compiling and using the SPDL programming language. SPDL (pronounced spiddle) stands for the Structured Parsing Description Language, and is used
to make parsing in a compiler much easier. This crate contains a function to compile SPDL into a parser, which can be used to turn code into syntax trees.

A syntactical instance, in this compiler's terms, is a syntactical structure describing parsing at a given point. This generated SPDL parser contains a root 
syntactical instance for the whole file, along with a set of syntactical instances for variables. Each of these syntactical instances has its own function for 
parsing at a point. 

The SPDLParser structure wraps around a root syntactical instance that parses at the start of the code and is expected to cover the whole of it. It also wraps
an array of all of the variables in the root syntactical instance. The SPDLParser structure contains a get_syntax_tree function which gets the syntax tree of 
input code based on the description of it's root syntactical instance, and returns a result that either contains errors or the output syntax tree.

Each syntactical instance has a certain syntactical instance type, and gives its resulting output of parsing at a point in input code. There are many types of 
syntactical instances currently available for usage in SPDL:

1. `Set(&[SyntacticalInstance])`

The "Set" syntactical instance type contains a set of syntactical instances to parse in order.

2. `ZeroOrMore(&SyntacticalInstance)`

The "ZeroOrMore" syntactical instance type asks the parser to parse a syntactical instance as many times as it can before giving up.

3. `OneOrMore(&SyntacticalInstance)`

Like ZeroOrMore, except for the fact that it requires a minimum of one iteration of successful parsing to succeed.

4. `Either(&[SyntacticalInstance])`

This allows for any one syntactical instances in a set to have parsed successfully at a point. This fails if none in the set are successful.

5. `Not(&SyntacticalInstance)`

The "Not" syntactical instance type disallows a certain syntactical instance to successfully parse at a point.

6. `Regular(&str)`

The "Regular" syntactical instance type parses successfully at a point if the current point starts with the string described in this syntactical instance type.

7. `Search(&str)`

The "Search" syntactical instance type serves as a runtime search for a syntactical instance with a specific name. Any invalid variable name in this will 
be detected at compile-time. This is needed when two or more variables are mutually dependent on each other, and hence can be used for recursion.

8. `Regex(Regex)`

The "Regex" syntactical instance type parses successfully if the current point in the input matches this regex.

9. `Questioned(&str, &SyntacticalInstance)`

This captures the result of parsing a syntactical instance (as in the second field), and parses the result with another syntactical instance (the name of this is in the first field).

An example of this crate's usage, parsing 300,000 print statements within less than a second on some computers, is as follows:

```rust
fn main() {
   let code = r#"
   print "Hello, world!";
   "#.repeat(300_000);

   let spdl_code = r##"
   freeform true
   string = /"[^"]*"/
   printStmt = print #string#;
   seterror printStmt Invalid print statement!
   parse printStmt
   "##;
   let parser = spdl::process_spdl(spdl_code);
   if parser.is_err() {
       let errors = parser.unwrap_err();
       for err in errors {
           println!("{}", err);
       }
       panic!("Failed test!");
   }
   let parser = parser.unwrap();

   let time = std::time::Instant::now();
   parser.get_syntax_tree(Box::leak(Box::new(code.into_boxed_str())), false).unwrap();
   println!("{:?}", time.elapsed());
}
```


The actual syntax of valid SPDL code consists of comments, variable declarations, freeform configurations, custom error-handling configurations, and a single parsing configuration.
SPDL is not a free-form language, except for with line breaks. Every line in SPDL code is trimmed on both ends before processing. Every comment in SPDL is a line 
that starts with a hashtag after being trimmed. Every line in SPDL must start and complete exactly one of these descriptions, or just be completely empty after trimming.

Every line that starts with a hashtag after trimming is a comment and is ignored. Every empty line after trimming is also ignored.

Every variable declaration has this rigid syntax:

`varName = sequence`

The sequence in the declaration can either be empty, or be one of the following syntactical descriptions:

`*sequenceGoesHere*` (This desribes a zero or more statement for a syntactical instance with the ZeroOrMore type)

`+sequenceGoesHere+` (This describes a one or more statement for a syntactical instance with the OneOrMore type)

`|sequenceGoesHere$maybeAnotherHere|` (This describes an either statement for a syntactical instance with the Either type)

`/regexGoesHere/` (This describes a regex statement for a syntactical instance with the Regex type)

`^sequenceGoesHere^` (This desribes a not statement for a syntactical instance with the Not type)

`&variableName&` (This describes a search statement for a syntactical instance with the Search type)

`?parseAs:sequenceGoesHere?` (This describes a parse statement for a syntactical instance with the Questioned type)

`#variableName#` (This includes a previously declared variable's syntax in the variable declaration)

`\punctuationGoesHere` (This describes an escape. No escape is invalid, but if a backslash is not followed by punctuation or a backslash, then it gets interpreted as a regular backslash followed by a regular character)

`regularSyntacticalInstance` (This describes a syntactical instance with the Regular type, consisting of a continous set of one or more escapes or non-punctuation characters)

Punctuation as mentioned above can be any of these characters separated by commas: *, +, |, /, ^. &, #, ?
Punctuation is used to specify the start of a different kind of syntactical instance in the sequence of syntactical instances in a variable declaration. Escapes give a way to remove their meaning.

Every custom error handling configuration in SPDL, which sets up a custom error to throw when parsing a variable fails, has the following syntax:

`seterror varName message`

The parsing configuration for SPDL code describing an SPDL parser tells which variable should be parsed recursively until the end of the input to the parser is reached. The syntax of such is as follows:

`parse varName`

Every freeform configuration in SPDL consists of the "freeform" keyword, followed by a single space, followed by true or false. This is to configure whether or not free-formedness 
is enabled after a certain line. Free-formedness is disabled by default, but has the effect of surrounding every regular syntactical instance in a variable declaration with regexes
to capture optional whitespace.
!*/

use regex::Regex;

#[derive(Clone, Copy, Debug)]
#[allow(missing_docs)]
/// All types of syntactical instances are described within this enum. Refer to the crate root docs and spdl_docs module's docs for more info.
pub enum SyntacticalInstanceKind {
    Questioned(&'static str, &'static SyntacticalInstance),
    ZeroOrMore(&'static SyntacticalInstance),
    OneOrMore(&'static SyntacticalInstance),
    Either(&'static [SyntacticalInstance]),
    Set(&'static [SyntacticalInstance]),
    Not(&'static SyntacticalInstance),
    Regular(&'static str),
    Search(&'static str),
    Regex(&'static Regex)
}

#[derive(Debug)]
enum Section {
    Hashtagged(usize, usize),
    Questioned(usize, usize),
    Starred(usize, usize),
    Regular(usize, usize),
    Plussed(usize, usize),
    Barred(usize, usize),
    Anded(usize, usize),
    Regex(usize, usize),
    Not(usize, usize),
}

trait Leak<T: ?Sized> {
    fn leak(self) -> &'static T; 
}

trait LeakBox<T: ?Sized> {
    fn leak_box(self) -> &'static T; 
}

impl<T: ?Sized> LeakBox<T> for Box<T> {
    fn leak_box(self) -> &'static T {
        Box::leak(self)
    }
}

impl Leak<str> for String {
    fn leak(self) -> &'static str {
        Box::leak(self.into_boxed_str())
    }
}

impl<T: Sized> Leak<[T]> for Vec<T> {
    fn leak(self) -> &'static [T] {
        Box::leak(self.into_boxed_slice())
    }
}

#[derive(Clone, Copy, Debug)]
/// This represents a syntactical instance.
pub struct SyntacticalInstance {
    /// The name of the syntactical instance.
    pub name: &'static str,
    /// The type of this syntactical instance.
    pub kind: SyntacticalInstanceKind,
    /// The error that this syntactical instance gives when it fails to parse, aside from the regular errors for invalid syntax.
    /// An empty string, which is the default value, means that no custom error is given.
    pub error_on_fail: &'static str
}

#[derive(Clone, Copy, Debug)]
/// This represents a SPDL parser.
pub struct SPDLParser {
    /// The root syntactical instance is a tree of syntactical instances that are parsed in order, to accomplish exhaustive parsing of the file.
    pub root: SyntacticalInstance,
    /// This is an array of all variables declared in the parser. This is used for syntactical instances with the type "Search" as a place to search for things in.
    pub vars: &'static [SyntacticalInstance]
}

#[derive(Clone, Copy, Debug)]
/// This represents a syntax tree.
pub struct SyntaxTree {
    /// The name of this branch of the syntax tree.
    pub branch: &'static str,
    /// The raw value of this branch of the syntax tree.
    pub branch_value: &'static str,
    /// An array of all branches that branch off this one in the syntax tree.
    pub branches: &'static [SyntaxTree]
}

#[derive(Clone, Copy, PartialEq)]
/// This represents an error output by a SPDL parser.
pub struct SPDLError {
    /// The value of the error.
    pub value: &'static str,
    /// The line on which the error occurred.
    pub line: usize,
    /// The column on which the error occurred.
    pub column: usize
}

impl std::fmt::Debug for SPDLError {
    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(formatter, "On line {}, column {}: {}", self.line, self.column, self.value)
    }
}

impl SPDLParser {
    /// This is a function that gets a syntax tree for input code based on the description of this parser.
    /// The trace parameter determines whether or not every step of parsing should be traced and printed out.
    pub fn get_syntax_tree(&self, input: &'static str, trace: bool) -> Result<SyntaxTree, Vec<SPDLError>> {
        let mut cpos = 0usize;
        let mut line = 1usize;
        let mut column = 0usize;
        let mut branches = Vec::new();
        let mut last_line_pos = 0usize;
        let mut parsed = SyntaxTree {
            branch: "Root",
            branch_value: input,
            branches: &[]
        };

        while cpos < input.len() - 1 {
            let now_parsed = self.root.parse_on(input, &mut cpos, &self.root.name, &mut line, &mut last_line_pos, &mut column, self, trace);
            if now_parsed.is_ok() {
                branches.push(now_parsed.unwrap());
            } else {
                return now_parsed;
            }
        }

        parsed.branches = branches.leak();
        Ok(parsed)
    }
}

impl SyntacticalInstance  {
    fn parse_on(&self, input: &'static str, cpos: &mut usize, branch: &'static str, line: &mut usize, last_lpos: &mut usize, column: &mut usize, top_level: &SPDLParser, trace: bool) -> Result<SyntaxTree, Vec<SPDLError>> {
        let mut branches = Vec::new();
        let mut errors: Vec<&'static str> = Vec::new();
        let mut positioned_errors: Vec<SPDLError> = Vec::new();
        let mut parsed: SyntaxTree = SyntaxTree {
            branch: branch,
            branch_value: "",
            branches: &[],
        };
        if trace {
            println!("At position {}: {}", cpos, self.name);
        }
        let origlen = errors.len();
        let orig_cpos: usize = *cpos;
        let orig_line: usize = *line;
        let orig_column: usize = *column;
        let mut branch_value = String::new();

        match self.kind {
            SyntacticalInstanceKind::ZeroOrMore(instance) => {
                let mut parsing = instance.parse_on(input, cpos, &instance.name, line, last_lpos, column, top_level, trace);
                while parsing.is_ok() {
                    branches.push(parsing.unwrap());
                    parsing = instance.parse_on(input, cpos, &instance.name, line, last_lpos, column, top_level, trace);
                }
            },

            SyntacticalInstanceKind::OneOrMore(instance) => {
                let mut parsing = instance.parse_on(input, cpos, &instance.name, line, last_lpos, column, top_level, trace);
                if parsing.is_err() {
                    positioned_errors = parsing.unwrap_err();
                } else {
                    while parsing.is_ok() {
                        branches.push(parsing.unwrap());
                        parsing = instance.parse_on(input, cpos, &instance.name, line, last_lpos, column, top_level, trace);
                    }
                }
            },

            SyntacticalInstanceKind::Either(instances) => {
                let mut hparsed = false;
                let mut parse_errs: Option<Vec<SPDLError>> = None;
                let mut min_pos = 0usize;
                
                for instance in instances.iter() {
                    let parsing = instance.parse_on(input, cpos, &instance.name, line, last_lpos, column, top_level, trace);
                    if parsing.is_ok() {
                        branches.push(parsing.unwrap());
                        hparsed = true;
                        break;
                    } else {
                        let errs = parsing.unwrap_err();
                        let current = errs.iter().max_by_key(|err| *last_lpos + err.column).unwrap().column + *last_lpos;
                        if current >= min_pos {
                            min_pos = current;
                            parse_errs = Some(errs);
                        }
                    }
                }

                if !hparsed {
                    positioned_errors.extend(parse_errs.unwrap().into_iter());
                }
            },

            SyntacticalInstanceKind::Set(instances) => {
                for instance in instances.iter() {
                    let parsing = instance.parse_on(input, cpos, &instance.name, line, last_lpos, column, top_level, trace);
                    if parsing.is_ok() {
                        branches.push(parsing.unwrap());
                    } else {
                        positioned_errors = parsing.unwrap_err();
                        break;
                    }
                }
            },

            SyntacticalInstanceKind::Regular(section) => {
                if input[*cpos..].starts_with(section) {
                    branch_value += section;
                    parsed.branches = Box::new([SyntaxTree {
                        branch: "Raw Syntax",
                        branch_value: section,
                        branches: &[]
                    }]).leak_box();
                    *cpos += section.len();
                } else {
                    errors.push(format!("Expected this: \"{}\"", section).leak());
                }
            },

            SyntacticalInstanceKind::Questioned(top, section) => {
                let res = section.parse_on(input, cpos, &section.name, line, last_lpos, column, top_level, trace);
                if res.is_ok() {
                    let finding = top_level.vars.iter().find(|x| x.name == top);
                    if finding.is_none() {
                        errors.push(format!("The variable {} does not exist in this file!", top).leak())
                    } else {
                        let branch = res.unwrap();
                        let res = SPDLParser {
                            root: finding.unwrap().clone(),
                            vars: &[]
                        }.get_syntax_tree(&branch.branch_value, trace);
                        if res.is_err() {
                            positioned_errors = res.unwrap_err();
                        } else {
                            parsed.branches = Box::new([branch, res.unwrap()]).leak_box();
                        }
                    }
                } else {
                    positioned_errors = res.unwrap_err();
                }
            },

            SyntacticalInstanceKind::Search(name) => {
                let finding = top_level.vars.iter().find(|x| x.name == name);
                if finding.is_none() {
                    panic!("Internal Parser Error: The syntactical instance \"{}\" doesn't exist in the parsing variable, but it was searched for!", name);
                } else {
                    let syntax = finding.unwrap();
                    let res = syntax.parse_on(input, cpos, name, line, last_lpos, column, top_level, trace);
                    if res.is_ok() {
                        parsed.branches = Box::new([res.unwrap()]).leak_box();
                    } else {
                        positioned_errors = res.unwrap_err();
                    }
                }
            },

            SyntacticalInstanceKind::Not(section) => {
                let parsing = section.parse_on(input, cpos, &section.name, line, last_lpos, column, top_level, trace);
                if parsing.is_err() {
                    parsed.branches = Box::new([SyntaxTree {
                        branch: "Not Statement",
                        branch_value: format!("{:#?}", section).leak(),
                        branches: &[]
                    }]).leak_box();
                } else {
                    errors.push(format!("Expected something thats isn't this syntactical instance: {}", section.name).leak());
                }
            },

            SyntacticalInstanceKind::Regex(regex) => {
                let find = regex.find_at(input, *cpos);
                if find.is_none() {
                    errors.push(format!("Expected something that fits this regex: {:?}", regex).leak());
                } else {
                    let finding = find.unwrap().as_str();
                    branch_value += finding;
                    parsed.branches = Box::new([SyntaxTree {
                        branch: "Regex Finding",
                        branch_value: finding.to_string().leak(),
                        branches: &[]
                    }]).leak_box();
                    *cpos += finding.len();
                }
            },
        }

        if parsed.branches.len() == 1 {
            parsed = parsed.branches[0].clone();
            parsed.branch = branch;
        }

        if errors.len() - origlen > 0 || positioned_errors.len() > 0 {
            positioned_errors.extend(errors.into_iter().map(|x| {
                SPDLError {
                    value: x,
                    column: *column,
                    line: *line,
                }
            }));

            *cpos = orig_cpos;
            *line = orig_line;
            *column = orig_column;
            Err(positioned_errors)
        } else {
            if parsed.branches.len() == 0 {
                parsed.branches = branches.leak();
            }
            if parsed.branches.len() != 0 {
                parsed.branch_value = parsed.branches.iter().map(|x| x.branch_value).collect::<String>().leak();
            } else {
                parsed.branch_value = branch_value.leak();
            }
            
            if *cpos < input.len() && input[orig_cpos..*cpos].contains("\n") {
                *last_lpos = *cpos;
                *column = 0;
                *line += 1;
            } else {
                *column = *cpos - orig_cpos;
            }
            Ok(parsed)
        }
    }
}

fn parse_instance(instances: &[SyntacticalInstance], inp: &'static str, name: &'static str, error_on_fail: &'static str, instnames: &'static [&'static str], freeform: bool) -> Result<SyntacticalInstance, &'static str> {
    let punctuation = ['*', '|', '+', '\\', '#', '/', '^', '?', '&'];

    let mut regular: Vec<(usize, usize)> = Vec::new();
    let mut hashtagged: Vec<usize> = Vec::new();
    let mut questioned: Vec<usize> = Vec::new();
    let mut starred: Vec<usize> = Vec::new();
    let mut plussed: Vec<usize> = Vec::new();
    let mut regexed: Vec<usize> = Vec::new();
    let mut notted: Vec<usize> = Vec::new();
    let mut barred: Vec<usize> = Vec::new();
    let mut anded: Vec<usize> = Vec::new();

    let valid_name = |name: &str| name.chars().all(char::is_alphanumeric);
    let unescape = |val: &str| val.replace("\\*", "*").replace("\\/", "/").replace("\\#", "#").replace("\\+", "+")
    .replace("\\?", "?").replace("\\|", "|").replace("\\^", "^").replace("\\&", "&").replace("\\b", "\\");
    let mut current_start = 0usize;
    let mut continuing = false;
    let mut in_section;

    let mut in_question = false;
    let mut in_hashtag = false;
    let mut in_plussed = false;
    let mut in_starred = false;
    let mut in_regged = false;
    let mut in_barred = false;
    let mut in_anded = false;
    let mut in_not = false;

    for (n, x) in inp.chars().enumerate() {
        if continuing {
            continuing = false;
            continue;
        }

        if punctuation.contains(&x) {
            in_section = in_hashtag || in_plussed || in_starred || in_regged || in_barred || in_not || in_question || in_anded;
            if current_start < n && !in_section {
                regular.push((current_start, n));
            }
            current_start = n + 1;
            if x != '\\' {
                let last = n;
                match x {
                    '#' => {
                        if in_hashtag || !in_section {
                            hashtagged.push(last);
                            in_hashtag = !in_hashtag;
                        }
                    },
                    '?' => {
                        if in_question && !in_section {
                            in_question = !in_question;
                            questioned.push(last);
                        }
                    },
                    '&' => {
                        if in_anded || !in_section {
                            anded.push(last);
                            in_anded = !in_anded;
                        }
                    },
                    '+' => {
                        if in_plussed || !in_section {
                            plussed.push(last);
                            in_plussed = !in_plussed;
                        }
                    },
                    '/' => {
                        if in_regged || !in_section {
                            regexed.push(last);
                            in_regged = !in_regged;
                        }
                    },
                    '*' => {
                        if in_starred || !in_section {
                            starred.push(last);
                            in_starred = !in_starred;
                        }
                    },
                    '|' => {
                        if in_barred || !in_section {
                            barred.push(last);
                            in_barred = !in_barred;
                        }
                    },
                    '^' => {
                        if in_not || !in_section {
                            notted.push(last);
                            in_not = !in_not;
                        }
                    },
                    _ => {
                        unreachable!();
                    }
                }
            } else if n == inp.len() - 1 {
                return Err("Invalid escape!");
            } else {
                continuing = true;
            }
        } else if n == inp.len() - 1 && current_start != n + 1 {
            regular.push((current_start, n + 1));
        }
    }

    let mut sections = Vec::new();

    if starred.len() % 2 != 0 {
        return Err("Unclosed zero-or-more statement!");
    }
    if plussed.len() % 2 != 0 {
        return Err("Unclosed one-or-more statement!");
    }
    if barred.len() % 2 != 0 {
        return Err("Unclosed either statement!");
    }
    if regexed.len() % 2 != 0 {
        return Err("Unclosed regex!");
    }
    if anded.len() % 2 != 0 {
        return Err("Unclosed search statement!");
    }
    if hashtagged.len() % 2 != 0 {
        return Err("Unclosed variable inclusion!");
    }
    if questioned.len() % 2 != 0 {
        return Err("Unclosed parse statement!");
    }
    if notted.len() % 2 != 0 {
        return Err("Unclosed not statement!");
    }

    let mut set: Vec<SyntacticalInstance> = Vec::new();

    if hashtagged.len() != 0 {
        for n in (0..hashtagged.len() - 1).step_by(2) {
            let start = hashtagged[n];
            let end = hashtagged[n + 1];
    
            sections.push(Section::Hashtagged(start + 1, end));
        }
    }

    if questioned.len() != 0 {
        for n in (0..questioned.len() - 1).step_by(2) {
            let start = questioned[n];
            let end = questioned[n + 1];
    
            sections.push(Section::Questioned(start + 1, end));
        }
    }

    if regexed.len() != 0 {
        for n in (0..regexed.len() - 1).step_by(2) {
            let start = regexed[n];
            let end = regexed[n + 1];
    
            sections.push(Section::Regex(start + 1, end));
        }
    }

    if starred.len() != 0 {
        for n in (0..starred.len() - 1).step_by(2) {
            let start = starred[n];
            let end = starred[n + 1];
    
            sections.push(Section::Starred(start + 1, end));
        }
    }
    
    if plussed.len() != 0 {
        for n in (0..plussed.len() - 1).step_by(2) {
            let start = plussed[n];
            let end = plussed[n + 1];
    
            sections.push(Section::Plussed(start + 1, end));
        }
    }

    if barred.len() != 0 {
        for n in (0..barred.len() - 1).step_by(2) {
            let start = barred[n];
            let end = barred[n + 1];
    
            sections.push(Section::Barred(start + 1, end));
        }    
    }

    if anded.len() != 0 {
        for n in (0..anded.len() - 1).step_by(2) {
            let start = anded[n];
            let end = anded[n + 1];
    
            sections.push(Section::Anded(start + 1, end));
        }    
    }

    if notted.len() != 0 {
        for n in (0..notted.len() - 1).step_by(2) {
            let start = notted[n];
            let end = notted[n + 1];
    
            sections.push(Section::Not(start + 1, end));
        }
    }

    if regular.len() != 0 {
        for r in regular.iter() {
            sections.push(Section::Regular(r.0, r.1));
        }
    }

    sections.sort_by(|a, b| {
        let measure = |x: &Section| -> usize {
            match x {
                Section::Hashtagged(x, _) | Section::Questioned(x, _) | Section::Regex(x, _) | Section::Anded(x, _) | 
                Section::Starred(x, _) | Section::Plussed(x, _) | Section::Barred(x, _) | Section::Regular(x, _) | 
                Section::Not(x, _) => {
                    *x
                }
            }
        };
        measure(a).cmp(&measure(b))
    });

    let optional_whitespace: SyntacticalInstance = SyntacticalInstance {
        name: "Freeform Whitespace",
        error_on_fail: "",
        kind: SyntacticalInstanceKind::Regex(Box::new(Regex::new(r"\s*").unwrap()).leak_box())
    };

    for sect in sections.iter() {
        match *sect {
            Section::Starred(start, end) => {
                let parsed = parse_instance(instances, &inp[start..end], name, "", instnames, freeform);
                if parsed.is_err() {
                    return parsed;
                } else {
                    let mut parsed = parsed.unwrap();
                    parsed.kind = SyntacticalInstanceKind::ZeroOrMore(Box::new(parsed.clone()).leak_box());
                    parsed.name = "Zero or More Statement";
                    parsed.error_on_fail = "";
                    set.push(parsed);
                }
            },

            Section::Plussed(start, end) => {
                let parsed = parse_instance(instances, &inp[start..end], name, "", instnames, freeform);
                if parsed.is_err() {
                    return parsed;
                } else {
                    let mut parsed = parsed.unwrap();
                    parsed.kind = SyntacticalInstanceKind::OneOrMore(Box::new(parsed.clone()).leak_box());
                    parsed.name = "One or More Statement";
                    parsed.error_on_fail = "";
                    set.push(parsed);
                }
            },

            Section::Barred(start, end) => {
                let section = &inp[start..end];
                let split = section.split("$");

                if split.clone().count() < 2 {
                    return Err("Invalid either statement! There must be a dollar sign splitting it.");
                }

                let mut parsed = Vec::new();
                for (n, slice) in split.enumerate() {
                    parsed.push(parse_instance(instances, slice, format!("Argument #{} of Either Statement", n).leak(), "", instnames, freeform));
                }
                let err = parsed.iter().find(|x| x.is_err());

                if err.is_some() {
                    return Err(err.as_ref().unwrap().as_ref().unwrap_err());
                } else {
                    set.push(SyntacticalInstance {
                        name: "Either Statement",
                        error_on_fail: "",
                        kind: SyntacticalInstanceKind::Either(
                            parsed.into_iter().map(|x| x.unwrap()).collect::<Vec<SyntacticalInstance>>().leak()
                        )
                    });
                }
            },

            Section::Regex(start, end) => {
                let section = &(inp[start..end].replace("\\/", "/"));
                let regex = Regex::new(&section);
                if regex.is_err() {
                    return Err(format!("Invalid regex due to error \"{}\": {}", regex.unwrap_err(), section).leak());
                } else {
                    let regex = regex.unwrap();
                    set.push(SyntacticalInstance {
                        name: format!("Regex Statement: {:?}", regex).leak(),
                        error_on_fail: "",
                        kind: SyntacticalInstanceKind::Regex(Box::new(regex).leak_box())
                    });
                }
            },

            Section::Hashtagged(start, end) => {
                let section = &inp[start..end];
                if !valid_name(&section) {
                    return Err(format!("Invalid variable name in variable inclusion: \"{}\"", section).leak());
                }

                let finding = instances.iter().position(|x| x.name == section);
                if finding.is_none() {
                    return Err(format!("No such valid variable has been declared yet in variable inclusion: {}", section).leak());
                }

                set.push(instances[finding.unwrap()].clone());
            },

            Section::Questioned(start, end) => {
                let section = &inp[start..end];
                let split = section.split(":").collect::<Vec<&str>>();
                if split.len() != 2 {
                    return Err(format!("Invalid parse statement, expected a colon to split it: {}", section).leak());
                }
                let res = parse_instance(instances, split[1], "Not Statement Innards", "", instnames, freeform);
                if res.is_err() {
                    return res;
                }
                set.push(SyntacticalInstance {
                    name: format!("Raw Syntax for Not Statement: {}", &inp[start..end]).leak(),
                    error_on_fail: "",
                    kind: SyntacticalInstanceKind::Questioned(split[0], Box::new(res.unwrap()).leak_box())
                });
            },

            Section::Anded(start, end) => {
                let section = &inp[start..end];
                if !instnames.contains(&section) {
                    return Err(format!("Invalid search statement: The variable \"{}\" is never declared!", section).leak());
                }
                set.push(SyntacticalInstance {
                    name: format!("Search Statement for \"{}\"", section).leak(),
                    error_on_fail: "",
                    kind: SyntacticalInstanceKind::Search(section)
                });
            },

            Section::Regular(start, end) => {
                let section = &inp[start..end];
                if freeform && !section.chars().all(|x| x.is_whitespace()) {
                    set.push(optional_whitespace.clone());
                }
                set.push(SyntacticalInstance {
                    name: format!("Raw Syntax: {}", &inp[start..end]).leak(),
                    error_on_fail: "",
                    kind: SyntacticalInstanceKind::Regular(unescape(section).leak())
                });
                if freeform {
                    set.push(optional_whitespace.clone());
                }
            },

            Section::Not(start, end) => {
                let res = parse_instance(instances, &inp[start..end], "Not Statement Innards", "", instnames, freeform);
                if res.is_err() {
                    return res;
                }
                set.push(SyntacticalInstance {
                    name: format!("Raw Syntax for Not Statement: {}", &inp[start..end]).leak(),
                    error_on_fail: "",
                    kind: SyntacticalInstanceKind::Not(Box::new(res.unwrap()).leak_box())
                });
            }
        }
    }

    if set.len() == 1 {
        set[0].name = name;
        set[0].error_on_fail = error_on_fail;
        Ok(set[0].clone())
    } else {
        Ok(SyntacticalInstance {
            name: name,
            error_on_fail: error_on_fail,
            kind: SyntacticalInstanceKind::Set(set.leak())
        })
    }
}

/// This turns SPDL code into an SPDL parser. If that fails, it returns an Err value containing a vector of errors.
pub fn process_spdl(spdl: &str) -> Result<SPDLParser, Vec<String>> {
    let mut errors: Vec<String> = Vec::new();
    let mut instances: Vec<SyntacticalInstance> = Vec::new();
    let mut parsing: Option<SyntacticalInstance> = None;
    let mut parsed = false;

    let mut instnames: Vec<&'static str> = Vec::new();
    for line in spdl.lines() {
        let line = line.trim();
        let split: Vec<&str> = line.split_whitespace().collect();
        if split.len() == 0 {
            continue;
        }
        match split[0] {
            "seterror" | "parse" | "freeform" => {},
            x => {
                instnames.push(Box::leak(x.to_string().into_boxed_str()));
            }
        }
    }

    let instnames: &'static [&'static str] = Box::leak(instnames.into_boxed_slice());
    let mut freeform = false;

    for (n, line) in spdl.lines().enumerate() {
        let line_trimmed = line.trim();
        let mut line = String::new();
        for character in line_trimmed.chars() {
            if character.is_whitespace() {
                line.push(' ');
            } else {
                line.push(character);
            }
        }
        let line: &'static str = line.leak();

        let mut line_err = |err: &str| errors.push(format!("Error on line {}: {}", n + 1, err));
        let valid_name = |name: &str| name.chars().all(|x| x.is_ascii_alphabetic());

        let split: Vec<&str> = line.split_whitespace().collect();
        let mut inds: Vec<usize> = Vec::new();
        let mut counter = 0usize;
        for x in split.iter() {
            counter += x.len() + 1;
            inds.push(counter);
        }

        if split.len() == 0 || line.starts_with("#") {
            continue;
        }

        match split[0] {
            "seterror" => {
                if split.len() < 2 {
                    line_err("Expected variable name after seterror keyword, got nothing!");
                    continue;
                }

                let name = split[1];
                if !valid_name(name) {
                    line_err("Invalid variable name for seterror!");
                    continue;
                }

                let finding = instances.iter_mut().find(|x| x.name == name);
                if finding.is_none() {
                    line_err(&format!("No such valid variable has been declared yet in seterror command: {}", name));
                    continue;
                }

                let mut finding: &mut SyntacticalInstance = finding.unwrap();
                finding.error_on_fail = if split.len() > 2 {
                    line[inds[1]..].to_string().leak()
                } else {
                    format!("Expected syntactical structure \"{}\"!", finding.name).leak()
                };
            },

            "parse" => {
                if split.len() < 2 {
                    line_err("Nothing specified after parse keyword!");
                    continue;
                }

                let res = instances.iter().find(|x| x.name == line[inds[0]..].to_string());
                if res.is_none() {
                    line_err("Expected a variable after parse keyword!");
                    continue;
                }
                parsed = true;
                parsing = Some(res.unwrap().clone());
            },

            "freeform" => {
                if split.len() != 2 {
                    line_err("Expected a boolean and nothing else after the freeform keyword!");
                }
                match split[1] {
                    "true" => {
                        freeform = true;
                    },
                    "false" => {
                        freeform = false;
                    },
                    _ => line_err("Invalid boolean after freeform keyword!")
                }
            },

            x => {
                if split.len() < 3 {
                    line_err("Too short of a variable declaration!");
                    continue;
                }

                if !valid_name(x) {
                    line_err(&format!("Invalid variable name for declaration: {}", x));
                    continue;
                }

                if split[1] != "=" {
                    line_err("Expected \"=\" after variable name in declaration with spaces around it.");
                    continue;
                }

                let res = parse_instance(
                    &instances, &line[inds[1]..], x, "", instnames, freeform
                );
                if res.is_err() {
                    line_err(&res.unwrap_err());
                    continue;
                }
                let mut res = res.unwrap();
                res.name = x;
                instances.push(res);
            }
        }
    }

    if !parsed {
        errors.push("Fatal Error: Nothing specified for parsing!".to_string());
    }
    
    if errors.len() > 0 {
        Err(errors)
    } else {
        Ok(SPDLParser {
            root: parsing.unwrap(),
            vars: instances.leak()
        })
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn printing_language() {
        let code = r#"
        print "Hello, world!";
        "#.repeat(300_000);

        let spdl = r##"
        freeform true
        string = /"[^"]*"/
        printStmt = print #string#;
        seterror printStmt Invalid print statement!
        parse printStmt
        "##;
        let parser = crate::process_spdl(spdl);
        if parser.is_err() {
            let errors = parser.unwrap_err();
            for err in errors {
                println!("{}", err);
            }
            panic!("Failed test!");
        }
        let parser = parser.unwrap();

        let time = std::time::Instant::now();
        parser.get_syntax_tree(Box::leak(Box::new(code.into_boxed_str())), false).unwrap();
        println!("{:?}", time.elapsed());
    }
}