From fa9404872efa17012f1991c1865d3db75debeda7 Mon Sep 17 00:00:00 2001
From: Chris Wong <lambda.fairy@gmail.com>
Date: Mon, 9 Feb 2015 15:05:50 +1300
Subject: [PATCH] Refactor toggleable attributes
---
maud_macros/src/parse.rs | 19 +++++++++++++++++--
maud_macros/src/render.rs | 28 +++++++++++-----------------
2 files changed, 28 insertions(+), 19 deletions(-)
diff --git a/maud_macros/src/parse.rs b/maud_macros/src/parse.rs
index aaa2a2a..84d674e 100644
--- a/maud_macros/src/parse.rs
+++ b/maud_macros/src/parse.rs
@@ -1,4 +1,4 @@
-use syntax::ast::{Expr, Lit, Stmt, TokenTree, TtDelimited, TtToken};
+use syntax::ast::{Expr, ExprParen, Lit, Stmt, TokenTree, TtDelimited, TtToken};
use syntax::codemap::Span;
use syntax::ext::base::ExtCtxt;
use syntax::parse;
@@ -207,7 +207,14 @@ impl<'cx, 's, 'i> Parser<'cx, 's, 'i> {
// Toggle the attribute based on a boolean expression
self.shift(1);
let cond = self.splice(tt.get_span());
- self.render.attribute_empty_if(name.as_str(), cond);
+ // Silence "unnecessary parentheses" warnings
+ let cond = strip_outer_parens(cond);
+ let body = {
+ let mut r = self.render.fork();
+ r.attribute_empty(name.as_str());
+ r.into_stmts()
+ };
+ self.render.emit_if(cond, body, None);
} else {
// Write the attribute unconditionally
self.render.attribute_empty(name.as_str());
@@ -249,3 +256,11 @@ fn lit_to_string(cx: &ExtCtxt, lit: Lit, minus: bool) -> Option<String> {
};
Some(result)
}
+
+/// If the expression is wrapped in parentheses, strip them off.
+fn strip_outer_parens(expr: P<Expr>) -> P<Expr> {
+ expr.and_then(|expr| match expr {
+ Expr { node: ExprParen(inner), .. } => inner,
+ expr => P(expr),
+ })
+}
diff --git a/maud_macros/src/render.rs b/maud_macros/src/render.rs
index dc87d24..9b3a97c 100644
--- a/maud_macros/src/render.rs
+++ b/maud_macros/src/render.rs
@@ -1,5 +1,5 @@
use std::borrow::IntoCow;
-use syntax::ast::{Expr, ExprParen, Ident, Stmt};
+use syntax::ast::{Expr, Ident, Stmt};
use syntax::ext::base::ExtCtxt;
use syntax::ext::build::AstBuilder;
use syntax::parse::token;
@@ -112,22 +112,6 @@ impl<'cx, 's> Renderer<'cx, 's> {
self.write(name);
}
- pub fn attribute_empty_if(&mut self, name: &str, cond: P<Expr>) {
- // Silence "unnecessary parentheses" warnings
- let cond = match cond.node {
- ExprParen(ref inner) => inner.clone(),
- _ => cond.clone(),
- };
- let body = {
- let mut r = self.fork();
- r.write(" ");
- r.write(name);
- r.into_stmts()
- };
- let stmt = quote_stmt!(self.cx, if $cond { $body });
- self.stmts.push(stmt);
- }
-
pub fn attribute_end(&mut self) {
self.write("\"");
}
@@ -141,4 +125,14 @@ impl<'cx, 's> Renderer<'cx, 's> {
self.write(name);
self.write(">");
}
+
+ pub fn emit_if(&mut self, cond: P<Expr>, if_body: Vec<P<Stmt>>,
+ else_body: Option<Vec<P<Stmt>>>) {
+ let stmt = match else_body {
+ None => quote_stmt!(self.cx, if $cond { $if_body }),
+ Some(else_body) =>
+ quote_stmt!(self.cx, if $cond { $if_body } else { $else_body }),
+ };
+ self.stmts.push(stmt);
+ }
}