rust/src/visitor.rs

573 lines
21 KiB
Rust

// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use syntax::ast;
use syntax::codemap::{self, CodeMap, Span, BytePos};
use syntax::parse::ParseSess;
use syntax::visit;
use strings::string_buffer::StringBuffer;
use {Indent, WriteMode};
use utils;
use config::Config;
use rewrite::{Rewrite, RewriteContext};
use comment::rewrite_comment;
use macros::rewrite_macro;
use items::rewrite_static;
pub struct FmtVisitor<'a> {
pub parse_session: &'a ParseSess,
pub codemap: &'a CodeMap,
pub buffer: StringBuffer,
pub last_pos: BytePos,
// TODO: RAII util for indenting
pub block_indent: Indent,
pub config: &'a Config,
pub write_mode: Option<WriteMode>,
}
impl<'a> FmtVisitor<'a> {
fn visit_stmt(&mut self, stmt: &ast::Stmt) {
match stmt.node {
ast::Stmt_::StmtDecl(ref decl, _) => {
match decl.node {
ast::Decl_::DeclLocal(ref local) => {
let rewrite = {
let context = self.get_context();
local.rewrite(&context, self.config.max_width, self.block_indent)
};
self.push_rewrite(stmt.span, rewrite);
}
ast::Decl_::DeclItem(ref item) => self.visit_item(item),
}
}
ast::Stmt_::StmtExpr(ref ex, _) | ast::Stmt_::StmtSemi(ref ex, _) => {
let suffix = if semicolon_for_stmt(stmt) {
";"
} else {
""
};
let rewrite = ex.rewrite(&self.get_context(),
self.config.max_width - self.block_indent.width() -
suffix.len(),
self.block_indent)
.map(|s| s + suffix);
self.push_rewrite(stmt.span, rewrite);
}
ast::Stmt_::StmtMac(ref mac, _macro_style) => {
self.format_missing_with_indent(stmt.span.lo);
self.visit_mac(mac);
}
}
}
pub fn visit_block(&mut self, b: &ast::Block) {
debug!("visit_block: {:?} {:?}",
self.codemap.lookup_char_pos(b.span.lo),
self.codemap.lookup_char_pos(b.span.hi));
// Check if this block has braces.
let snippet = self.snippet(b.span);
let has_braces = &snippet[..1] == "{" || &snippet[..6] == "unsafe";
let brace_compensation = if has_braces {
BytePos(1)
} else {
BytePos(0)
};
self.last_pos = self.last_pos + brace_compensation;
self.block_indent = self.block_indent.block_indent(self.config);
self.buffer.push_str("{");
for stmt in &b.stmts {
self.visit_stmt(&stmt)
}
if let Some(ref e) = b.expr {
self.format_missing_with_indent(e.span.lo);
let rewrite = e.rewrite(&self.get_context(),
self.config.max_width - self.block_indent.width(),
self.block_indent)
.unwrap_or_else(|| self.snippet(e.span));
self.buffer.push_str(&rewrite);
self.last_pos = e.span.hi;
if semicolon_for_expr(e) {
self.buffer.push_str(";");
}
}
// TODO: we should compress any newlines here to just one
self.format_missing_with_indent(b.span.hi - brace_compensation);
// FIXME: this is a terrible hack to indent the comments between the last
// item in the block and the closing brace to the block's level.
// The closing brace itself, however, should be indented at a shallower
// level.
let total_len = self.buffer.len;
let chars_too_many = if self.config.hard_tabs {
1
} else {
self.config.tab_spaces
};
self.buffer.truncate(total_len - chars_too_many);
self.buffer.push_str("}");
self.last_pos = b.span.hi;
self.block_indent = self.block_indent.block_unindent(self.config);
}
// Note that this only gets called for function definitions. Required methods
// on traits do not get handled here.
fn visit_fn(&mut self,
fk: visit::FnKind,
fd: &ast::FnDecl,
b: &ast::Block,
s: Span,
_: ast::NodeId) {
let indent = self.block_indent;
let rewrite = match fk {
visit::FnKind::ItemFn(ident, ref generics, unsafety, constness, abi, vis) => {
self.rewrite_fn(indent,
ident,
fd,
None,
generics,
unsafety,
constness,
abi,
vis,
codemap::mk_sp(s.lo, b.span.lo))
}
visit::FnKind::Method(ident, ref sig, vis) => {
self.rewrite_fn(indent,
ident,
fd,
Some(&sig.explicit_self),
&sig.generics,
sig.unsafety,
sig.constness,
sig.abi,
vis.unwrap_or(ast::Visibility::Inherited),
codemap::mk_sp(s.lo, b.span.lo))
}
visit::FnKind::Closure => None,
};
if let Some(fn_str) = rewrite {
self.format_missing_with_indent(s.lo);
self.buffer.push_str(&fn_str);
} else {
self.format_missing(b.span.lo);
}
self.last_pos = b.span.lo;
self.visit_block(b)
}
fn visit_item(&mut self, item: &ast::Item) {
// Don't look at attributes for modules.
// We want to avoid looking at attributes in another file, which the AST
// doesn't distinguish. FIXME This is overly conservative and means we miss
// attributes on inline modules.
match item.node {
ast::Item_::ItemMod(_) => {}
_ => {
if self.visit_attrs(&item.attrs) {
return;
}
}
}
match item.node {
ast::Item_::ItemUse(ref vp) => {
self.format_import(item.vis, vp, item.span);
}
// FIXME(#78): format impl definitions.
ast::Item_::ItemImpl(_, _, _, _, _, ref impl_items) => {
self.format_missing_with_indent(item.span.lo);
self.block_indent = self.block_indent.block_indent(self.config);
for item in impl_items {
self.visit_impl_item(&item);
}
self.block_indent = self.block_indent.block_unindent(self.config);
}
// FIXME(#78): format traits.
ast::Item_::ItemTrait(_, _, _, ref trait_items) => {
self.format_missing_with_indent(item.span.lo);
self.block_indent = self.block_indent.block_indent(self.config);
for item in trait_items {
self.visit_trait_item(&item);
}
self.block_indent = self.block_indent.block_unindent(self.config);
}
ast::Item_::ItemExternCrate(_) => {
self.format_missing_with_indent(item.span.lo);
let new_str = self.snippet(item.span);
self.buffer.push_str(&new_str);
self.last_pos = item.span.hi;
}
ast::Item_::ItemStruct(ref def, ref generics) => {
let indent = self.block_indent;
let rewrite = self.format_struct("struct ",
item.ident,
item.vis,
def,
Some(generics),
item.span,
indent)
.map(|s| {
match **def {
ast::VariantData::Tuple(..) => s + ";",
_ => s,
}
});
self.push_rewrite(item.span, rewrite);
}
ast::Item_::ItemEnum(ref def, ref generics) => {
self.format_missing_with_indent(item.span.lo);
self.visit_enum(item.ident, item.vis, def, generics, item.span);
self.last_pos = item.span.hi;
}
ast::Item_::ItemMod(ref module) => {
self.format_missing_with_indent(item.span.lo);
self.format_mod(module, item.span, item.ident);
}
ast::Item_::ItemMac(..) => {
self.format_missing_with_indent(item.span.lo);
let snippet = self.snippet(item.span);
self.buffer.push_str(&snippet);
self.last_pos = item.span.hi;
// FIXME: we cannot format these yet, because of a bad span.
// See rust lang issue #28424.
}
ast::Item_::ItemForeignMod(ref foreign_mod) => {
self.format_missing_with_indent(item.span.lo);
self.format_foreign_mod(foreign_mod, item.span);
}
ast::Item_::ItemStatic(ref ty, mutability, ref expr) => {
let rewrite = rewrite_static("static",
item.vis,
item.ident,
ty,
mutability,
expr,
&self.get_context());
self.push_rewrite(item.span, rewrite);
}
ast::Item_::ItemConst(ref ty, ref expr) => {
let rewrite = rewrite_static("const",
item.vis,
item.ident,
ty,
ast::Mutability::MutImmutable,
expr,
&self.get_context());
self.push_rewrite(item.span, rewrite);
}
ast::Item_::ItemDefaultImpl(..) => {
// FIXME(#78): format impl definitions.
}
ast::ItemFn(ref declaration, unsafety, constness, abi, ref generics, ref body) => {
self.visit_fn(visit::FnKind::ItemFn(item.ident,
generics,
unsafety,
constness,
abi,
item.vis),
declaration,
body,
item.span,
item.id)
}
ast::Item_::ItemTy(..) => {
// FIXME(#486): format type aliases.
}
}
}
fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
if self.visit_attrs(&ti.attrs) {
return;
}
match ti.node {
ast::ConstTraitItem(..) => {
// FIXME: Implement
}
ast::MethodTraitItem(ref sig, None) => {
let indent = self.block_indent;
let rewrite = self.rewrite_required_fn(indent, ti.ident, sig, ti.span);
self.push_rewrite(ti.span, rewrite);
}
ast::MethodTraitItem(ref sig, Some(ref body)) => {
self.visit_fn(visit::FnKind::Method(ti.ident, sig, None),
&sig.decl,
&body,
ti.span,
ti.id);
}
ast::TypeTraitItem(..) => {
// FIXME: Implement
}
}
}
fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
if self.visit_attrs(&ii.attrs) {
return;
}
match ii.node {
ast::MethodImplItem(ref sig, ref body) => {
self.visit_fn(visit::FnKind::Method(ii.ident, sig, Some(ii.vis)),
&sig.decl,
body,
ii.span,
ii.id);
}
ast::ConstImplItem(..) => {
// FIXME: Implement
}
ast::TypeImplItem(_) => {
// FIXME: Implement
}
ast::MacImplItem(ref mac) => {
self.visit_mac(mac);
}
}
}
fn visit_mac(&mut self, mac: &ast::Mac) {
// 1 = ;
let width = self.config.max_width - self.block_indent.width() - 1;
let rewrite = rewrite_macro(mac, &self.get_context(), width, self.block_indent);
if let Some(res) = rewrite {
self.buffer.push_str(&res);
self.last_pos = mac.span.hi;
}
}
fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
self.format_missing_with_indent(span.lo);
if let Some(res) = rewrite {
self.buffer.push_str(&res);
self.last_pos = span.hi;
}
}
pub fn from_codemap(parse_session: &'a ParseSess,
config: &'a Config,
mode: Option<WriteMode>)
-> FmtVisitor<'a> {
FmtVisitor {
parse_session: parse_session,
codemap: parse_session.codemap(),
buffer: StringBuffer::new(),
last_pos: BytePos(0),
block_indent: Indent {
block_indent: 0,
alignment: 0,
},
config: config,
write_mode: mode,
}
}
pub fn snippet(&self, span: Span) -> String {
match self.codemap.span_to_snippet(span) {
Ok(s) => s,
Err(_) => {
println!("Couldn't make snippet for span {:?}->{:?}",
self.codemap.lookup_char_pos(span.lo),
self.codemap.lookup_char_pos(span.hi));
"".to_owned()
}
}
}
// Returns true if we should skip the following item.
pub fn visit_attrs(&mut self, attrs: &[ast::Attribute]) -> bool {
if attrs.is_empty() {
return false;
}
if utils::contains_skip(attrs) {
return true;
}
let outers: Vec<_> = attrs.iter()
.filter(|a| a.node.style == ast::AttrStyle::Outer)
.map(|a| a.clone())
.collect();
if outers.is_empty() {
return false;
}
let first = &outers[0];
self.format_missing_with_indent(first.span.lo);
let rewrite = outers.rewrite(&self.get_context(),
self.config.max_width - self.block_indent.width(),
self.block_indent)
.unwrap();
self.buffer.push_str(&rewrite);
let last = outers.last().unwrap();
self.last_pos = last.span.hi;
false
}
fn walk_mod_items(&mut self, m: &ast::Mod) {
for item in &m.items {
self.visit_item(&item);
}
}
fn format_mod(&mut self, m: &ast::Mod, s: Span, ident: ast::Ident) {
debug!("FmtVisitor::format_mod: ident: {:?}, span: {:?}", ident, s);
// Decide whether this is an inline mod or an external mod.
let local_file_name = self.codemap.span_to_filename(s);
let is_internal = local_file_name == self.codemap.span_to_filename(m.inner);
// TODO: Should rewrite properly `mod X;`
if is_internal {
self.block_indent = self.block_indent.block_indent(self.config);
self.walk_mod_items(m);
self.block_indent = self.block_indent.block_unindent(self.config);
self.format_missing_with_indent(m.inner.hi - BytePos(1));
self.buffer.push_str("}");
self.last_pos = m.inner.hi;
}
}
pub fn format_separate_mod(&mut self, m: &ast::Mod, filename: &str) {
let filemap = self.codemap.get_filemap(filename);
self.last_pos = filemap.start_pos;
self.block_indent = Indent::empty();
self.walk_mod_items(m);
self.format_missing(filemap.end_pos);
}
fn format_import(&mut self, vis: ast::Visibility, vp: &ast::ViewPath, span: Span) {
let vis = utils::format_visibility(vis);
let mut offset = self.block_indent;
offset.alignment += vis.len() + "use ".len();
// 1 = ";"
match vp.rewrite(&self.get_context(),
self.config.max_width - offset.width() - 1,
offset) {
Some(ref s) if s.is_empty() => {
// Format up to last newline
let prev_span = codemap::mk_sp(self.last_pos, span.lo);
let span_end = match self.snippet(prev_span).rfind('\n') {
Some(offset) => self.last_pos + BytePos(offset as u32),
None => span.lo,
};
self.format_missing(span_end);
self.last_pos = span.hi;
}
Some(ref s) => {
let s = format!("{}use {};", vis, s);
self.format_missing_with_indent(span.lo);
self.buffer.push_str(&s);
self.last_pos = span.hi;
}
None => {
self.format_missing_with_indent(span.lo);
self.format_missing(span.hi);
}
}
}
pub fn get_context(&self) -> RewriteContext {
RewriteContext {
parse_session: self.parse_session,
codemap: self.codemap,
config: self.config,
block_indent: self.block_indent,
}
}
}
fn semicolon_for_stmt(stmt: &ast::Stmt) -> bool {
match stmt.node {
ast::Stmt_::StmtSemi(ref expr, _) => {
match expr.node {
ast::Expr_::ExprWhile(..) |
ast::Expr_::ExprWhileLet(..) |
ast::Expr_::ExprLoop(..) |
ast::Expr_::ExprForLoop(..) => false,
_ => true,
}
}
ast::Stmt_::StmtExpr(..) => false,
_ => true,
}
}
fn semicolon_for_expr(expr: &ast::Expr) -> bool {
match expr.node {
ast::Expr_::ExprRet(..) |
ast::Expr_::ExprAgain(..) |
ast::Expr_::ExprBreak(..) => true,
_ => false,
}
}
impl<'a> Rewrite for [ast::Attribute] {
fn rewrite(&self, context: &RewriteContext, _: usize, offset: Indent) -> Option<String> {
let mut result = String::new();
if self.is_empty() {
return Some(result);
}
let indent = offset.to_string(context.config);
for (i, a) in self.iter().enumerate() {
let a_str = context.snippet(a.span);
if i > 0 {
let comment = context.snippet(codemap::mk_sp(self[i - 1].span.hi, a.span.lo));
// This particular horror show is to preserve line breaks in between doc
// comments. An alternative would be to force such line breaks to start
// with the usual doc comment token.
let multi_line = a_str.starts_with("//") && comment.matches('\n').count() > 1;
let comment = comment.trim();
if !comment.is_empty() {
let comment = try_opt!(rewrite_comment(comment,
false,
context.config.max_width -
offset.width(),
offset,
context.config));
result.push_str(&indent);
result.push_str(&comment);
result.push('\n');
} else if multi_line {
result.push('\n');
}
result.push_str(&indent);
}
result.push_str(&a_str);
if i < self.len() - 1 {
result.push('\n');
}
}
Some(result)
}
}