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pub mod modifier;
pub mod operator;
pub mod variable;
use std::fmt::Write;
use crate::{
string::{
satisfy,
Encode,
Satisfy,
},
template::{
component::expression::{
modifier::Modifier,
operator::Operator,
variable::VariableList,
},
Expand,
ExpandError,
Parse,
ParseError,
TryParse,
},
value::{
Value,
Values,
},
};
// =============================================================================
// Expression
// =============================================================================
// Types
#[derive(Debug, Eq, PartialEq)]
pub struct Expression<'t> {
operator: Option<Operator>,
variable_list: VariableList<'t>,
}
impl<'t> Expression<'t> {
const fn new(operator: Option<Operator>, variable_list: VariableList<'t>) -> Self {
Self {
operator,
variable_list,
}
}
}
// -----------------------------------------------------------------------------
// Parse
impl<'t> TryParse<'t> for Expression<'t> {
fn try_parse(raw: &'t str, global: usize) -> Result<(usize, Self), ParseError> {
let mut parsed_operator = None;
let mut parsed_variable_list = Vec::new();
let mut state = ExpressionState::default();
loop {
let rest = &raw[state.position..];
match &state.next {
ExpressionNext::OpeningBrace if rest.starts_with('{') => {
state.next = ExpressionNext::Operator;
state.position += 1;
}
ExpressionNext::OpeningBrace => {
return Err(ParseError::UnexpectedInput {
position: global + state.position,
message: "unexpected input when parsing expression component".into(),
expected: "opening brace ('{')".into(),
});
}
ExpressionNext::Operator => {
let (position, operator) =
Option::<Operator>::parse(rest, global + state.position);
parsed_operator = operator;
state.next = ExpressionNext::VariableList;
state.position += position;
}
ExpressionNext::VariableList => {
match VariableList::try_parse(rest, global + state.position) {
Ok((position, variable_list)) => {
parsed_variable_list.extend(variable_list);
state.next = ExpressionNext::ClosingBrace;
state.position += position;
}
Err(err) => return Err(err),
}
}
ExpressionNext::ClosingBrace if rest.starts_with('}') => {
state.position += 1;
return Ok((
state.position,
Self::new(parsed_operator, parsed_variable_list),
));
}
ExpressionNext::ClosingBrace => {
return Err(ParseError::UnexpectedInput {
position: global + state.position,
message: "unexpected input when parsing expression component".into(),
expected: "closing brace ('}')".into(),
});
}
}
}
}
}
#[derive(Default)]
struct ExpressionState {
next: ExpressionNext,
position: usize,
}
#[derive(Default)]
enum ExpressionNext {
#[default]
OpeningBrace,
Operator,
VariableList,
ClosingBrace,
}
// -----------------------------------------------------------------------------
// Expand
impl<'t> Expand for Expression<'t> {
#[allow(clippy::cognitive_complexity)] // TODO: Reduce?
#[allow(clippy::equatable_if_let)]
#[allow(clippy::too_many_lines)]
fn expand(&self, values: &Values, write: &mut impl Write) -> Result<(), ExpandError> {
let behaviour = self
.operator
.as_ref()
.map_or(&operator::DEFAULT_BEHAVIOUR, Operator::behaviour);
let satisfier = behaviour.allow.satisfier();
let mut first = true;
for (var_name, modifier) in &self.variable_list {
// Lookup the value for the scanned variable name, and then
//
// * If the varname is unknown or corresponds to a variable with an undefined
// value (Section 2.3), then skip to the next varspec.
let value = match values.get(var_name.name()) {
Some(value) if value.defined() => value,
_ => continue,
};
// * If this is the first defined variable for this expression, append the first
// string for this expression type to the result string and remember that it
// has been done. Otherwise, append the sep string to the result string.
if first {
if let Some(c) = behaviour.first {
write.write_char(c)?;
}
first = false;
} else {
write.write_char(behaviour.sep)?;
}
if let Value::Item(value) = value {
// If this variable's value is a string, then
if behaviour.named {
// * if named is true, append the varname to the result string using the same
// encoding process as for literals, and
write.encode(var_name.name(), &satisfy::unreserved_or_reserved())?;
if value.is_empty() {
// + if the value is empty, append the ifemp string to the result string and
// skip to the next varspec;
if let Some(c) = behaviour.ifemp {
write.write_char(c)?;
}
} else {
// + otherwise, append "=" to the result string.
write.write_char('=')?;
}
}
match modifier {
Some(Modifier::Prefix(length)) => {
// * if a prefix modifier is present and the prefix length is less than the
// value string length in number of Unicode characters, append that number
// of characters from the beginning of the value string to the result
// string, after pct-encoding any characters that are not in the allow
// set, while taking care not to split multi-octet or pct-encoded triplet
// characters that represent a single Unicode code point;
let pos: usize = value.chars().take(*length).map(char::len_utf8).sum();
write.encode(&value[..pos], &satisfier)?;
}
_ => {
// * otherwise, append the value to the result string after pct-encoding any
// characters that are not in the allow set.
write.encode(value, &satisfier)?;
}
};
} else if let Some(Modifier::Explode) = modifier {
// else if an explode modifier is given, then
if behaviour.named {
// * if named is true, then for each defined list member or array (name, value)
// pair with a defined value, do:
if let Value::AssociativeArray(value) = value {
let mut first = true;
for (name, value) in value {
// + if this is not the first defined member/value, append the sep
// string to the result string;
if first {
first = false;
} else {
write.write_char(behaviour.sep)?;
}
// + if this is a pair, append the name to the result string using the
// same encoding process as for literals;
write.encode(name, &satisfy::unreserved_or_reserved())?;
// + if the member/value is empty, append the ifemp string to the result
// string; otherwise, append "=" and the member/value to the result
// string, after pct-encoding any member/value characters that are not
// in the allow set.
if value.is_empty() {
if let Some(c) = behaviour.ifemp {
write.write_char(c)?;
}
} else {
write.write_char('=')?;
write.encode(value, &satisfier)?;
}
}
} else if let Value::List(value) = value {
let mut first = true;
for value in value {
// + if this is not the first defined member/value, append the sep
// string to the result string;
if first {
first = false;
} else {
write.write_char(behaviour.sep)?;
}
// + if this is a list, append the varname to the result string using
// the same encoding process as for literals;
write.encode(var_name.name(), &satisfy::unreserved_or_reserved())?;
// + if the member/value is empty, append the ifemp string to the result
// string; otherwise, append "=" and the member/value to the result
// string, after pct-encoding any member/value characters that are not
// in the allow set.
if value.is_empty() {
if let Some(c) = behaviour.ifemp {
write.write_char(c)?;
}
} else {
write.write_char('=')?;
write.encode(value, &satisfier)?;
}
}
}
} else {
// * else if named is false, then
if let Value::AssociativeArray(value) = value {
// + if this is an array of (name, value) pairs, append each pair with a
// defined value to the result string as "name=value", after pct-encoding
// any characters that are not in the allow set, with the sep string
// appended to the result between each defined pair.
let mut first = true;
for (name, value) in value {
if !value.is_empty() {
if first {
first = false;
} else {
write.write_char(behaviour.sep)?;
}
}
write.encode(name, &satisfier)?;
write.write_char('=')?;
write.encode(value, &satisfier)?;
}
} else if let Value::List(value) = value {
// + if this is a list, append each defined list member to the result
// string, after pct-encoding any characters that are not in the allow
// set, with the sep string appended to the result between each defined
// list member.
let mut first = true;
for value in value {
if !value.is_empty() {
if first {
first = false;
} else {
write.write_char(behaviour.sep)?;
}
}
write.encode(value, &satisfier)?;
}
}
}
} else {
// else if no explode modifier is given, then
if behaviour.named {
// * if named is true, append the varname to the result string using the same
// encoding process as for literals, and
write.encode(var_name.name(), &satisfy::unreserved_or_reserved())?;
// + if the value is empty, append the ifemp string to the result string and
// skip to the next varspec;
// + otherwise, append "=" to the result string; and
// NOTE: Empty values are not meaningful currently, so this logic is skipped for
// now
write.write_char('=')?;
}
if let Value::AssociativeArray(value) = value {
// * if this variable's value is an associative array or any other form of
// paired (name, value) structure, append each pair with defined value to the
// result string as "name,value", after pct-encoding any characters that are
// not in the allow set, with a comma (",") appended to the result between
// each defined pair.
let mut first = true;
for (name, value) in value {
if !value.is_empty() {
if first {
first = false;
} else {
write.write_char(',')?;
}
write.encode(name, &satisfier)?;
write.write_char(',')?;
write.encode(value, &satisfier)?;
}
}
} else if let Value::List(value) = value {
// * if this variable's value is a list, append each defined list member to the
// result string, after pct-encoding any characters that are not in the allow
// set, with a comma (",") appended to the result between each defined list
// member;
let mut first = true;
for value in value {
if !value.is_empty() {
if first {
first = false;
} else {
write.write_char(',')?;
}
write.encode(value, &satisfier)?;
}
}
}
}
}
Ok(())
}
}
#[derive(Debug)]
pub struct Behaviour {
pub first: Option<char>,
pub sep: char,
pub named: bool,
pub ifemp: Option<char>,
pub allow: Allow,
}
#[derive(Debug)]
pub enum Allow {
U,
UR,
}
impl Allow {
pub fn satisfier(&self) -> Box<dyn Satisfy> {
match self {
Self::U => Box::new(satisfy::unreserved()),
Self::UR => Box::new(satisfy::unreserved_or_reserved()),
}
}
}