rust/src/visitor.rs
2018-06-07 15:20:01 +09:00

770 lines
28 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::attr::HasAttrs;
use syntax::codemap::{self, BytePos, CodeMap, Pos, Span};
use syntax::parse::ParseSess;
use syntax::{ast, visit};
use attr::*;
use codemap::{LineRangeUtils, SpanUtils};
use comment::{CodeCharKind, CommentCodeSlices, FindUncommented};
use config::{BraceStyle, Config};
use items::{
format_impl, format_trait, format_trait_alias, is_mod_decl, is_use_item,
rewrite_associated_impl_type, rewrite_associated_type, rewrite_extern_crate,
rewrite_type_alias, FnSig, StaticParts, StructParts,
};
use macros::{rewrite_macro, rewrite_macro_def, MacroPosition};
use rewrite::{Rewrite, RewriteContext};
use shape::{Indent, Shape};
use spanned::Spanned;
use utils::{
self, contains_skip, count_newlines, inner_attributes, mk_sp, ptr_vec_to_ref_vec,
DEPR_SKIP_ANNOTATION,
};
use {ErrorKind, FormatReport, FormattingError};
use std::cell::RefCell;
/// Creates a string slice corresponding to the specified span.
pub struct SnippetProvider<'a> {
/// A pointer to the content of the file we are formatting.
big_snippet: &'a str,
/// A position of the start of `big_snippet`, used as an offset.
start_pos: usize,
}
impl<'a> SnippetProvider<'a> {
pub fn span_to_snippet(&self, span: Span) -> Option<&str> {
let start_index = span.lo().to_usize().checked_sub(self.start_pos)?;
let end_index = span.hi().to_usize().checked_sub(self.start_pos)?;
Some(&self.big_snippet[start_index..end_index])
}
pub fn new(start_pos: BytePos, big_snippet: &'a str) -> Self {
let start_pos = start_pos.to_usize();
SnippetProvider {
big_snippet,
start_pos,
}
}
}
pub struct FmtVisitor<'a> {
pub parse_session: &'a ParseSess,
pub codemap: &'a CodeMap,
pub buffer: String,
pub last_pos: BytePos,
// FIXME: use an RAII util or closure for indenting
pub block_indent: Indent,
pub config: &'a Config,
pub is_if_else_block: bool,
pub snippet_provider: &'a SnippetProvider<'a>,
pub line_number: usize,
pub skipped_range: Vec<(usize, usize)>,
pub macro_rewrite_failure: bool,
pub(crate) report: FormatReport,
}
impl<'b, 'a: 'b> FmtVisitor<'a> {
pub fn shape(&self) -> Shape {
Shape::indented(self.block_indent, self.config)
}
fn visit_stmt(&mut self, stmt: &ast::Stmt) {
debug!(
"visit_stmt: {:?} {:?}",
self.codemap.lookup_char_pos(stmt.span.lo()),
self.codemap.lookup_char_pos(stmt.span.hi())
);
match stmt.node {
ast::StmtKind::Item(ref item) => {
self.visit_item(item);
}
ast::StmtKind::Local(..) | ast::StmtKind::Expr(..) | ast::StmtKind::Semi(..) => {
if contains_skip(get_attrs_from_stmt(stmt)) {
self.push_skipped_with_span(stmt.span());
} else {
let rewrite = stmt.rewrite(&self.get_context(), self.shape());
self.push_rewrite(stmt.span(), rewrite)
}
}
ast::StmtKind::Mac(ref mac) => {
let (ref mac, _macro_style, ref attrs) = **mac;
if self.visit_attrs(attrs, ast::AttrStyle::Outer) {
self.push_skipped_with_span(stmt.span());
} else {
self.visit_mac(mac, None, MacroPosition::Statement);
}
self.format_missing(stmt.span.hi());
}
}
}
pub fn visit_block(
&mut self,
b: &ast::Block,
inner_attrs: Option<&[ast::Attribute]>,
has_braces: bool,
) {
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 brace_compensation = BytePos(if has_braces { 1 } else { 0 });
self.last_pos = self.last_pos + brace_compensation;
self.block_indent = self.block_indent.block_indent(self.config);
self.push_str("{");
if let Some(first_stmt) = b.stmts.first() {
let attr_lo = inner_attrs
.and_then(|attrs| inner_attributes(attrs).first().map(|attr| attr.span.lo()))
.or_else(|| {
// Attributes for an item in a statement position
// do not belong to the statement. (rust-lang/rust#34459)
if let ast::StmtKind::Item(ref item) = first_stmt.node {
item.attrs.first()
} else {
first_stmt.attrs().first()
}.and_then(|attr| {
// Some stmts can have embedded attributes.
// e.g. `match { #![attr] ... }`
let attr_lo = attr.span.lo();
if attr_lo < first_stmt.span.lo() {
Some(attr_lo)
} else {
None
}
})
});
let snippet = self.snippet(mk_sp(
self.last_pos,
attr_lo.unwrap_or_else(|| first_stmt.span.lo()),
));
let len = CommentCodeSlices::new(snippet)
.nth(0)
.and_then(|(kind, _, s)| {
if kind == CodeCharKind::Normal {
s.rfind('\n')
} else {
None
}
});
if let Some(len) = len {
self.last_pos = self.last_pos + BytePos::from_usize(len);
}
}
// Format inner attributes if available.
let skip_rewrite = if let Some(attrs) = inner_attrs {
self.visit_attrs(attrs, ast::AttrStyle::Inner)
} else {
false
};
if skip_rewrite {
self.push_rewrite(b.span, None);
self.close_block(false);
self.last_pos = source!(self, b.span).hi();
return;
}
self.walk_block_stmts(b);
if !b.stmts.is_empty() {
if let Some(expr) = utils::stmt_expr(&b.stmts[b.stmts.len() - 1]) {
if utils::semicolon_for_expr(&self.get_context(), expr) {
self.push_str(";");
}
}
}
let mut remove_len = BytePos(0);
if let Some(stmt) = b.stmts.last() {
let snippet = self.snippet(mk_sp(
stmt.span.hi(),
source!(self, b.span).hi() - brace_compensation,
));
let len = CommentCodeSlices::new(snippet)
.last()
.and_then(|(kind, _, s)| {
if kind == CodeCharKind::Normal && s.trim().is_empty() {
Some(s.len())
} else {
None
}
});
if let Some(len) = len {
remove_len = BytePos::from_usize(len);
}
}
let unindent_comment = (self.is_if_else_block && !b.stmts.is_empty()) && {
let end_pos = source!(self, b.span).hi() - brace_compensation - remove_len;
let snippet = self.snippet(mk_sp(self.last_pos, end_pos));
snippet.contains("//") || snippet.contains("/*")
};
// FIXME: we should compress any newlines here to just one
if unindent_comment {
self.block_indent = self.block_indent.block_unindent(self.config);
}
self.format_missing_with_indent(
source!(self, b.span).hi() - brace_compensation - remove_len,
);
if unindent_comment {
self.block_indent = self.block_indent.block_indent(self.config);
}
self.close_block(unindent_comment);
self.last_pos = source!(self, b.span).hi();
}
// 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.
fn close_block(&mut self, unindent_comment: bool) {
let total_len = self.buffer.len();
let chars_too_many = if unindent_comment {
0
} else if self.config.hard_tabs() {
1
} else {
self.config.tab_spaces()
};
self.buffer.truncate(total_len - chars_too_many);
self.push_str("}");
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,
generics: &ast::Generics,
fd: &ast::FnDecl,
s: Span,
defaultness: ast::Defaultness,
inner_attrs: Option<&[ast::Attribute]>,
) {
let indent = self.block_indent;
let block;
let rewrite = match fk {
visit::FnKind::ItemFn(ident, _, _, _, _, b) | visit::FnKind::Method(ident, _, _, b) => {
block = b;
self.rewrite_fn(
indent,
ident,
&FnSig::from_fn_kind(&fk, generics, fd, defaultness),
mk_sp(s.lo(), b.span.lo()),
b,
inner_attrs,
)
}
visit::FnKind::Closure(_) => unreachable!(),
};
if let Some(fn_str) = rewrite {
self.format_missing_with_indent(source!(self, s).lo());
self.push_str(&fn_str);
if let Some(c) = fn_str.chars().last() {
if c == '}' {
self.last_pos = source!(self, block.span).hi();
return;
}
}
} else {
self.format_missing(source!(self, block.span).lo());
}
self.last_pos = source!(self, block.span).lo();
self.visit_block(block, inner_attrs, true)
}
pub fn visit_item(&mut self, item: &ast::Item) {
skip_out_of_file_lines_range_visitor!(self, item.span);
// This is where we bail out if there is a skip attribute. This is only
// complex in the module case. It is complex because the module could be
// in a separate file and there might be attributes in both files, but
// the AST lumps them all together.
let filtered_attrs;
let mut attrs = &item.attrs;
match item.node {
// For use items, skip rewriting attributes. Just check for a skip attribute.
ast::ItemKind::Use(..) => {
if contains_skip(attrs) {
self.push_skipped_with_span(item.span());
return;
}
}
// Module is inline, in this case we treat it like any other item.
_ if !is_mod_decl(item) => {
if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
self.push_skipped_with_span(item.span());
return;
}
}
// Module is not inline, but should be skipped.
ast::ItemKind::Mod(..) if contains_skip(&item.attrs) => {
return;
}
// Module is not inline and should not be skipped. We want
// to process only the attributes in the current file.
ast::ItemKind::Mod(..) => {
filtered_attrs = filter_inline_attrs(&item.attrs, item.span());
// Assert because if we should skip it should be caught by
// the above case.
assert!(!self.visit_attrs(&filtered_attrs, ast::AttrStyle::Outer));
attrs = &filtered_attrs;
}
_ => {
if self.visit_attrs(&item.attrs, ast::AttrStyle::Outer) {
self.push_skipped_with_span(item.span());
return;
}
}
}
match item.node {
ast::ItemKind::Use(ref tree) => self.format_import(item, tree),
ast::ItemKind::Impl(..) => {
let snippet = self.snippet(item.span);
let where_span_end = snippet
.find_uncommented("{")
.map(|x| BytePos(x as u32) + source!(self, item.span).lo());
let rw = format_impl(&self.get_context(), item, self.block_indent, where_span_end);
self.push_rewrite(item.span, rw);
}
ast::ItemKind::Trait(..) => {
let rw = format_trait(&self.get_context(), item, self.block_indent);
self.push_rewrite(item.span, rw);
}
ast::ItemKind::TraitAlias(ref generics, ref ty_param_bounds) => {
let shape = Shape::indented(self.block_indent, self.config);
let rw = format_trait_alias(
&self.get_context(),
item.ident,
generics,
ty_param_bounds,
shape,
);
self.push_rewrite(item.span, rw);
}
ast::ItemKind::ExternCrate(_) => {
let rw = rewrite_extern_crate(&self.get_context(), item);
self.push_rewrite(item.span, rw);
}
ast::ItemKind::Struct(..) | ast::ItemKind::Union(..) => {
self.visit_struct(&StructParts::from_item(item));
}
ast::ItemKind::Enum(ref def, ref generics) => {
self.format_missing_with_indent(source!(self, item.span).lo());
self.visit_enum(item.ident, &item.vis, def, generics, item.span);
self.last_pos = source!(self, item.span).hi();
}
ast::ItemKind::Mod(ref module) => {
let is_inline = !is_mod_decl(item);
self.format_missing_with_indent(source!(self, item.span).lo());
self.format_mod(module, &item.vis, item.span, item.ident, attrs, is_inline);
}
ast::ItemKind::Mac(ref mac) => {
self.visit_mac(mac, Some(item.ident), MacroPosition::Item);
}
ast::ItemKind::ForeignMod(ref foreign_mod) => {
self.format_missing_with_indent(source!(self, item.span).lo());
self.format_foreign_mod(foreign_mod, item.span);
}
ast::ItemKind::Static(..) | ast::ItemKind::Const(..) => {
self.visit_static(&StaticParts::from_item(item));
}
ast::ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => {
let inner_attrs = inner_attributes(&item.attrs);
self.visit_fn(
visit::FnKind::ItemFn(item.ident, unsafety, constness, abi, &item.vis, body),
generics,
decl,
item.span,
ast::Defaultness::Final,
Some(&inner_attrs),
)
}
ast::ItemKind::Ty(ref ty, ref generics) => {
let rewrite = rewrite_type_alias(
&self.get_context(),
self.block_indent,
item.ident,
ty,
generics,
&item.vis,
item.span,
);
self.push_rewrite(item.span, rewrite);
}
ast::ItemKind::GlobalAsm(..) => {
let snippet = Some(self.snippet(item.span).to_owned());
self.push_rewrite(item.span, snippet);
}
ast::ItemKind::MacroDef(ref def) => {
let rewrite = rewrite_macro_def(
&self.get_context(),
self.shape(),
self.block_indent,
def,
item.ident,
&item.vis,
item.span,
);
self.push_rewrite(item.span, rewrite);
}
}
}
pub fn visit_trait_item(&mut self, ti: &ast::TraitItem) {
skip_out_of_file_lines_range_visitor!(self, ti.span);
if self.visit_attrs(&ti.attrs, ast::AttrStyle::Outer) {
self.push_skipped_with_span(ti.span());
return;
}
match ti.node {
ast::TraitItemKind::Const(..) => self.visit_static(&StaticParts::from_trait_item(ti)),
ast::TraitItemKind::Method(ref sig, None) => {
let indent = self.block_indent;
let rewrite =
self.rewrite_required_fn(indent, ti.ident, sig, &ti.generics, ti.span);
self.push_rewrite(ti.span, rewrite);
}
ast::TraitItemKind::Method(ref sig, Some(ref body)) => {
let inner_attrs = inner_attributes(&ti.attrs);
self.visit_fn(
visit::FnKind::Method(ti.ident, sig, None, body),
&ti.generics,
&sig.decl,
ti.span,
ast::Defaultness::Final,
Some(&inner_attrs),
);
}
ast::TraitItemKind::Type(ref type_param_bounds, ref type_default) => {
let rewrite = rewrite_associated_type(
ti.ident,
type_default.as_ref(),
Some(type_param_bounds),
&self.get_context(),
self.block_indent,
);
self.push_rewrite(ti.span, rewrite);
}
ast::TraitItemKind::Macro(ref mac) => {
self.visit_mac(mac, Some(ti.ident), MacroPosition::Item);
}
}
}
pub fn visit_impl_item(&mut self, ii: &ast::ImplItem) {
skip_out_of_file_lines_range_visitor!(self, ii.span);
if self.visit_attrs(&ii.attrs, ast::AttrStyle::Outer) {
self.push_skipped_with_span(ii.span());
return;
}
match ii.node {
ast::ImplItemKind::Method(ref sig, ref body) => {
let inner_attrs = inner_attributes(&ii.attrs);
self.visit_fn(
visit::FnKind::Method(ii.ident, sig, Some(&ii.vis), body),
&ii.generics,
&sig.decl,
ii.span,
ii.defaultness,
Some(&inner_attrs),
);
}
ast::ImplItemKind::Const(..) => self.visit_static(&StaticParts::from_impl_item(ii)),
ast::ImplItemKind::Type(ref ty) => {
let rewrite = rewrite_associated_impl_type(
ii.ident,
ii.defaultness,
Some(ty),
None,
&self.get_context(),
self.block_indent,
);
self.push_rewrite(ii.span, rewrite);
}
ast::ImplItemKind::Macro(ref mac) => {
self.visit_mac(mac, Some(ii.ident), MacroPosition::Item);
}
}
}
fn visit_mac(&mut self, mac: &ast::Mac, ident: Option<ast::Ident>, pos: MacroPosition) {
skip_out_of_file_lines_range_visitor!(self, mac.span);
// 1 = ;
let shape = self.shape().sub_width(1).unwrap();
let rewrite = self.with_context(|ctx| rewrite_macro(mac, ident, ctx, shape, pos));
self.push_rewrite(mac.span, rewrite);
}
pub fn push_str(&mut self, s: &str) {
self.line_number += count_newlines(s);
self.buffer.push_str(s);
}
#[cfg_attr(feature = "cargo-clippy", allow(needless_pass_by_value))]
fn push_rewrite_inner(&mut self, span: Span, rewrite: Option<String>) {
if let Some(ref s) = rewrite {
self.push_str(s);
} else {
let snippet = self.snippet(span);
self.push_str(snippet);
}
self.last_pos = source!(self, span).hi();
}
pub fn push_rewrite(&mut self, span: Span, rewrite: Option<String>) {
self.format_missing_with_indent(source!(self, span).lo());
self.push_rewrite_inner(span, rewrite);
}
pub fn push_skipped_with_span(&mut self, span: Span) {
self.format_missing_with_indent(source!(self, span).lo());
let lo = self.line_number + 1;
self.push_rewrite_inner(span, None);
let hi = self.line_number + 1;
self.skipped_range.push((lo, hi));
}
pub fn from_context(ctx: &'a RewriteContext) -> FmtVisitor<'a> {
FmtVisitor::from_codemap(
ctx.parse_session,
ctx.config,
ctx.snippet_provider,
ctx.report.clone(),
)
}
pub(crate) fn from_codemap(
parse_session: &'a ParseSess,
config: &'a Config,
snippet_provider: &'a SnippetProvider,
report: FormatReport,
) -> FmtVisitor<'a> {
FmtVisitor {
parse_session,
codemap: parse_session.codemap(),
buffer: String::with_capacity(snippet_provider.big_snippet.len() * 2),
last_pos: BytePos(0),
block_indent: Indent::empty(),
config,
is_if_else_block: false,
snippet_provider,
line_number: 0,
skipped_range: vec![],
macro_rewrite_failure: false,
report,
}
}
pub fn opt_snippet(&'b self, span: Span) -> Option<&'a str> {
self.snippet_provider.span_to_snippet(span)
}
pub fn snippet(&'b self, span: Span) -> &'a str {
self.opt_snippet(span).unwrap()
}
// Returns true if we should skip the following item.
pub fn visit_attrs(&mut self, attrs: &[ast::Attribute], style: ast::AttrStyle) -> bool {
for attr in attrs {
if attr.name() == DEPR_SKIP_ANNOTATION {
let file_name = self.codemap.span_to_filename(attr.span).into();
self.report.append(
file_name,
vec![FormattingError::from_span(
&attr.span,
&self.codemap,
ErrorKind::DeprecatedAttr,
)],
);
} else if attr.path.segments[0].ident.to_string() == "rustfmt" {
if attr.path.segments.len() == 1
|| attr.path.segments[1].ident.to_string() != "skip"
{
let file_name = self.codemap.span_to_filename(attr.span).into();
self.report.append(
file_name,
vec![FormattingError::from_span(
&attr.span,
&self.codemap,
ErrorKind::BadAttr,
)],
);
}
}
}
if contains_skip(attrs) {
return true;
}
let attrs: Vec<_> = attrs.iter().filter(|a| a.style == style).cloned().collect();
if attrs.is_empty() {
return false;
}
let rewrite = attrs.rewrite(&self.get_context(), self.shape());
let span = mk_sp(attrs[0].span.lo(), attrs[attrs.len() - 1].span.hi());
self.push_rewrite(span, rewrite);
false
}
fn walk_mod_items(&mut self, m: &ast::Mod) {
self.visit_items_with_reordering(&ptr_vec_to_ref_vec(&m.items));
}
fn walk_stmts(&mut self, stmts: &[ast::Stmt]) {
fn to_stmt_item(stmt: &ast::Stmt) -> Option<&ast::Item> {
match stmt.node {
ast::StmtKind::Item(ref item) => Some(&**item),
_ => None,
}
}
if stmts.is_empty() {
return;
}
// Extract leading `use ...;`.
let items: Vec<_> = stmts
.iter()
.take_while(|stmt| to_stmt_item(stmt).map_or(false, is_use_item))
.filter_map(|stmt| to_stmt_item(stmt))
.collect();
if items.is_empty() {
self.visit_stmt(&stmts[0]);
self.walk_stmts(&stmts[1..]);
} else {
self.visit_items_with_reordering(&items);
self.walk_stmts(&stmts[items.len()..]);
}
}
fn walk_block_stmts(&mut self, b: &ast::Block) {
self.walk_stmts(&b.stmts)
}
fn format_mod(
&mut self,
m: &ast::Mod,
vis: &ast::Visibility,
s: Span,
ident: ast::Ident,
attrs: &[ast::Attribute],
is_internal: bool,
) {
self.push_str(&*utils::format_visibility(vis));
self.push_str("mod ");
self.push_str(&ident.to_string());
if is_internal {
match self.config.brace_style() {
BraceStyle::AlwaysNextLine => {
let indent_str = self.block_indent.to_string_with_newline(self.config);
self.push_str(&indent_str);
self.push_str("{");
}
_ => self.push_str(" {"),
}
// Hackery to account for the closing }.
let mod_lo = self.snippet_provider.span_after(source!(self, s), "{");
let body_snippet =
self.snippet(mk_sp(mod_lo, source!(self, m.inner).hi() - BytePos(1)));
let body_snippet = body_snippet.trim();
if body_snippet.is_empty() {
self.push_str("}");
} else {
self.last_pos = mod_lo;
self.block_indent = self.block_indent.block_indent(self.config);
self.visit_attrs(attrs, ast::AttrStyle::Inner);
self.walk_mod_items(m);
self.format_missing_with_indent(source!(self, m.inner).hi() - BytePos(1));
self.close_block(false);
}
self.last_pos = source!(self, m.inner).hi();
} else {
self.push_str(";");
self.last_pos = source!(self, s).hi();
}
}
pub fn format_separate_mod(&mut self, m: &ast::Mod, filemap: &codemap::FileMap) {
self.block_indent = Indent::empty();
self.walk_mod_items(m);
self.format_missing_with_indent(filemap.end_pos);
}
pub fn skip_empty_lines(&mut self, end_pos: BytePos) {
while let Some(pos) = self
.snippet_provider
.opt_span_after(mk_sp(self.last_pos, end_pos), "\n")
{
if let Some(snippet) = self.opt_snippet(mk_sp(self.last_pos, pos)) {
if snippet.trim().is_empty() {
self.last_pos = pos;
} else {
return;
}
}
}
}
pub fn with_context<F>(&mut self, f: F) -> Option<String>
where
F: Fn(&RewriteContext) -> Option<String>,
{
let result;
let macro_rewrite_failure = {
let context = self.get_context();
result = f(&context);
unsafe { *context.macro_rewrite_failure.as_ptr() }
};
self.macro_rewrite_failure |= macro_rewrite_failure;
result
}
pub fn get_context(&self) -> RewriteContext {
RewriteContext {
parse_session: self.parse_session,
codemap: self.codemap,
config: self.config,
inside_macro: RefCell::new(false),
use_block: RefCell::new(false),
is_if_else_block: RefCell::new(false),
force_one_line_chain: RefCell::new(false),
snippet_provider: self.snippet_provider,
macro_rewrite_failure: RefCell::new(false),
report: self.report.clone(),
}
}
}