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use quote::{quote_spanned, ToTokens};
use syn::parse::{Parse, ParseStream, Result};
use syn::{Token, Expr, Pat, braced};
use syn::token::{Brace};
use crate::xtext::XtextCrumb;
pub enum XtextExprInner {
S(Expr),
E(Expr),
F(Token![for],Pat,Expr,Vec<XtextCrumb>),
W(Token![while],Expr,Vec<XtextCrumb>),
L(Token![let],Pat,Expr),
I(Token![if],Expr,Vec<XtextCrumb>,Vec<(Expr,Vec<XtextCrumb>)>,Vec<XtextCrumb>),
P(Token![loop],Vec<XtextCrumb>),
}
impl ToTokens for XtextExprInner {
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
match self {
XtextExprInner::E(e) => {
(quote_spanned!{ syn::spanned::Spanned::span(e)=>
stream.push_str(&#e.to_string());
}).to_tokens(tokens);
}, XtextExprInner::S(e) => {
(quote_spanned!{ syn::spanned::Spanned::span(e)=>
#e;
}).to_tokens(tokens);
}, XtextExprInner::F(f,p,i,cs) => {
(quote_spanned!{f.span=>
for #p in #i { #(#cs)* }
}).to_tokens(tokens);
}, XtextExprInner::P(l,cs) => {
(quote_spanned!{l.span=>
loop { #(#cs)* }
}).to_tokens(tokens);
}, XtextExprInner::I(i,c,bs,es,e) => {
(quote_spanned!{i.span=>
if #c { #(#bs)* }
}).to_tokens(tokens);
for (c,e) in es.iter() {
(quote_spanned!{i.span=>
else if #c { #(#e)* }
}).to_tokens(tokens);
}
if e.len() > 0 {
(quote_spanned!{i.span=>
else { #(#e)* }
}).to_tokens(tokens);
}
}, XtextExprInner::W(w,i,cs) => {
(quote_spanned!{w.span=>
while #i { #(#cs)* }
}).to_tokens(tokens);
}, XtextExprInner::L(t,l,e) => {
(quote_spanned!{t.span=>
let #l = #e;
}).to_tokens(tokens);
}
}
}
}
impl Parse for XtextExprInner {
fn parse(input: ParseStream) -> Result<Self> {
if input.peek(Token![for]) {
let _for: Token![for] = input.parse()?;
let pat: Pat = input.parse()?;
let _in: Token![in] = input.parse()?;
let iter: Expr = input.parse()?;
let content;
let content2;
let _brace1 = braced!(content in input);
let _brace2 = braced!(content2 in content);
let body: Vec<XtextCrumb> = content2.call(XtextCrumb::parse_outer)?;
Ok(XtextExprInner::F(_for,pat,iter,body))
} else if input.peek(Token![loop]) {
let _loop: Token![loop] = input.parse()?;
let content;
let content2;
let _brace1 = braced!(content in input);
let _brace2 = braced!(content2 in content);
let body: Vec<XtextCrumb> = content2.call(XtextCrumb::parse_outer)?;
Ok(XtextExprInner::P(_loop,body))
} else if input.peek(Token![while]) {
let _while: Token![while] = input.parse()?;
let iter: Expr = input.parse()?;
let content;
let content2;
let _brace1 = braced!(content in input);
let _brace2 = braced!(content2 in content);
let body: Vec<XtextCrumb> = content2.call(XtextCrumb::parse_outer)?;
Ok(XtextExprInner::W(_while,iter,body))
} else if input.peek(Token![if]) {
let _if: Token![if] = input.parse()?;
let b: Expr = input.parse()?;
let mut es = Vec::new();
let mut e = Vec::new();
let content;
let content2;
let _brace1 = braced!(content in input);
let _brace2 = braced!(content2 in content);
let body: Vec<XtextCrumb> = content2.call(XtextCrumb::parse_outer)?;
while input.peek(Token![else]) && input.peek2(Token![if]) {
let _else: Token![else] = input.parse()?;
let _if: Token![if] = input.parse()?;
let b: Expr = input.parse()?;
let content;
let content2;
let _brace1 = braced!(content in input);
let _brace2 = braced!(content2 in content);
let e = content2.call(XtextCrumb::parse_outer)?;
es.push((b,e));
}
if input.peek(Token![else]) {
let _else: Token![else] = input.parse()?;
let content;
let content2;
let _brace1 = braced!(content in input);
let _brace2 = braced!(content2 in content);
e = content2.call(XtextCrumb::parse_outer)?;
}
Ok(XtextExprInner::I(_if,b,body,es,e))
} else if input.peek(Token![let]) {
let _let: Token![let] = input.parse()?;
let pat: Pat = input.parse()?;
let _eq: Token![=] = input.parse()?;
let expr: Expr = input.parse()?;
if input.peek(Token![;]) {
let _: Token![;] = input.parse()?;
}
Ok(XtextExprInner::L(_let,pat,expr))
} else {
let e: Expr = input.parse()?;
if input.peek(Token![;]) {
let _semi: Token![;] = input.parse()?;
Ok(XtextExprInner::S(e))
} else {
Ok(XtextExprInner::E(e))
}
}
}
}
pub struct XtextExpr {
pub brace_token1: Brace,
pub brace_token2: Brace,
pub expr: XtextExprInner
}
impl Parse for XtextExpr {
fn parse(input: ParseStream) -> Result<Self> {
let _content;
let content2;
Ok(XtextExpr {
brace_token1: braced!(_content in input),
brace_token2: braced!(content2 in _content),
expr: content2.call(XtextExprInner::parse)?,
})
}
}
impl ToTokens for XtextExpr {
fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
self.expr.to_tokens(tokens)
}
}