Teach the tokenizer to report escaped newlines

Add fields and flags so that escaped newlines can be reported, for the
benefit of fish_indent.

src/parse_tree.cpp

@@ -270,7 +270,10 @@ static void dump_tree_recursive(const parse_node_tree_t &nodes, const wcstring &
         append_format(*result, L" <%lu children>", node.child_count);
     }
     if (node.has_comments()) {
-        append_format(*result, L" <has_comments>", node.child_count);
+        append_format(*result, L" <has_comments>");
+    }
+    if (node.has_preceding_escaped_newline()) {
+        append_format(*result, L" <preceding_esc_nl>");
     }
 
     if (node.has_source() && node.type == parse_token_type_string) {
@@ -357,7 +360,7 @@ class parse_ll_t {
     parse_error_list_t errors;
     // The symbol stack can contain terminal types or symbols. Symbols go on to do productions, but
     // terminal types are just matched against input tokens.
-    bool top_node_handle_terminal_types(parse_token_t token);
+    bool top_node_handle_terminal_types(const parse_token_t &token);
 
     void parse_error_unexpected_token(const wchar_t *expected, parse_token_t token);
     void parse_error(parse_token_t token, parse_error_code_t code, const wchar_t *format, ...);
@@ -758,7 +761,7 @@ bool parse_ll_t::report_error_for_unclosed_block() {
     return reported_error;
 }
 
-bool parse_ll_t::top_node_handle_terminal_types(parse_token_t token) {
+bool parse_ll_t::top_node_handle_terminal_types(const parse_token_t &token) {
     PARSE_ASSERT(!symbol_stack.empty());  //!OCLINT(multiple unary operator)
     PARSE_ASSERT(token.type >= FIRST_PARSE_TOKEN_TYPE);
     parse_stack_element_t &stack_top = symbol_stack.back();
@@ -791,6 +794,8 @@ bool parse_ll_t::top_node_handle_terminal_types(parse_token_t token) {
         node.keyword = token.keyword;
         node.source_start = token.source_start;
         node.source_length = token.source_length;
+        if (token.preceding_escaped_nl)
+            node.flags |= parse_node_flag_preceding_escaped_nl;
     } else {
         // Failure
         if (stack_top.type == parse_token_type_string && token.type == parse_token_type_string) {
@@ -858,6 +863,8 @@ void parse_ll_t::accept_tokens(parse_token_t token1, parse_token_t token2) {
         special_node.parent = symbol_stack.back().node_idx;
         special_node.source_start = token1.source_start;
         special_node.source_length = token1.source_length;
+        if (token1.preceding_escaped_nl)
+            special_node.flags |= parse_node_flag_preceding_escaped_nl;
         nodes.push_back(special_node);
 
         // Mark special flags.
@@ -969,12 +976,10 @@ static parse_keyword_t keyword_for_token(token_type tok, const wcstring &token)
 }
 
 /// Placeholder invalid token.
-static constexpr parse_token_t kInvalidToken = {
-    token_type_invalid, parse_keyword_none, false, false, false, SOURCE_OFFSET_INVALID, 0};
+static constexpr parse_token_t kInvalidToken{token_type_invalid};
 
 /// Terminal token.
-static constexpr parse_token_t kTerminalToken = {
-    parse_token_type_terminate, parse_keyword_none, false, false, false, SOURCE_OFFSET_INVALID, 0};
+static constexpr parse_token_t kTerminalToken = {parse_token_type_terminate};
 
 static inline bool is_help_argument(const wcstring &txt) {
     return txt == L"-h" || txt == L"--help";
@@ -986,19 +991,18 @@ static inline parse_token_t next_parse_token(tokenizer_t *tok, tok_t *token, wcs
         return kTerminalToken;
     }
 
-    parse_token_t result;
-
     // Set the type, keyword, and whether there's a dash prefix. Note that this is quite sketchy,
     // because it ignores quotes. This is the historical behavior. For example, `builtin --names`
     // lists builtins, but `builtin "--names"` attempts to run --names as a command. Amazingly as of
     // this writing (10/12/13) nobody seems to have noticed this. Squint at it really hard and it
     // even starts to look like a feature.
-    result.type = parse_token_type_from_tokenizer_token(token->type);
+    parse_token_t result{parse_token_type_from_tokenizer_token(token->type)};
     const wcstring &text = tok->copy_text_of(*token, storage);
     result.keyword = keyword_for_token(token->type, text);
     result.has_dash_prefix = !text.empty() && text.at(0) == L'-';
     result.is_help_argument = result.has_dash_prefix && is_help_argument(text);
     result.is_newline = (result.type == parse_token_type_end && text == L"\n");
+    result.preceding_escaped_nl = token->preceding_escaped_nl;
 
     // These assertions are totally bogus. Basically our tokenizer works in size_t but we work in
     // uint32_t to save some space. If we have a source file larger than 4 GB, we'll probably just
@@ -1079,13 +1083,9 @@ bool parse_tree_from_string(const wcstring &str, parse_tree_flags_t parse_flags,
         }
 
         // Mark a special error token, and then keep going.
-        const parse_token_t token = {parse_special_type_parse_error,
-                                     parse_keyword_none,
-                                     false,
-                                     false,
-                                     false,
-                                     queue[error_token_idx].source_start,
-                                     queue[error_token_idx].source_length};
+        parse_token_t token = {parse_special_type_parse_error};
+        token.source_start = queue[error_token_idx].source_start;
+        token.source_length = queue[error_token_idx].source_length;
         parser.accept_tokens(token, kInvalidToken);
         parser.reset_symbols(goal);
     }

src/parse_tree.h

@@ -28,15 +28,18 @@ constexpr source_offset_t SOURCE_OFFSET_INVALID = static_cast<source_offset_t>(-
 /// A struct representing the token type that we use internally.
 struct parse_token_t {
     enum parse_token_type_t type;  // The type of the token as represented by the parser
-    enum parse_keyword_t keyword;  // Any keyword represented by this token
-    bool has_dash_prefix;          // Hackish: whether the source contains a dash prefix
-    bool is_help_argument;         // Hackish: whether the source looks like '-h' or '--help'
-    bool is_newline;               // Hackish: if TOK_END, whether the source is a newline.
-    source_offset_t source_start;
-    source_offset_t source_length;
+    enum parse_keyword_t keyword{parse_keyword_none};  // Any keyword represented by this token
+    bool has_dash_prefix{false};          // Hackish: whether the source contains a dash prefix
+    bool is_help_argument{false};         // Hackish: whether the source looks like '-h' or '--help'
+    bool is_newline{false};               // Hackish: if TOK_END, whether the source is a newline.
+    bool preceding_escaped_nl{false};     // Whether there was an escaped newline preceding this token.
+    source_offset_t source_start{SOURCE_OFFSET_INVALID};
+    source_offset_t source_length{0};
 
     wcstring describe() const;
     wcstring user_presentable_description() const;
+
+    constexpr parse_token_t(parse_token_type_t type) : type(type) {}
 };
 
 enum {
@@ -66,6 +69,11 @@ const wchar_t *keyword_description(parse_keyword_t type);
 enum {
     /// Flag indicating that the node has associated comment nodes.
     parse_node_flag_has_comments = 1 << 0,
+
+    /// Flag indicating that the token was preceded by an escaped newline, e.g.
+    ///   echo abc | \
+    ///      cat
+    parse_node_flag_preceding_escaped_nl = 1 << 1,
 };
 typedef uint8_t parse_node_flags_t;
 
@@ -123,7 +131,12 @@ class parse_node_t {
 
     /// Indicate if the node has comment nodes.
     bool has_comments() const {
-        return static_cast<bool>(this->flags & parse_node_flag_has_comments);
+        return this->flags & parse_node_flag_has_comments;
+    }
+
+    /// Indicates if we have a preceding escaped newline.
+    bool has_preceding_escaped_newline() const {
+        return this->flags & parse_node_flag_preceding_escaped_nl;
     }
 
     /// Gets source for the node, or the empty string if it has no source.

src/tokenizer.cpp

@@ -428,10 +428,12 @@ maybe_t<tok_t> tokenizer_t::tok_next() {
     }
 
     // Consume non-newline whitespace. If we get an escaped newline, mark it and continue past it.
+    bool preceding_escaped_nl = false;
     for (;;) {
         if (this->buff[0] == L'\\' && this->buff[1] == L'\n') {
             this->buff += 2;
             this->continue_line_after_comment = true;
+            preceding_escaped_nl = true;
         } else if (iswspace_not_nl(this->buff[0])) {
             this->buff++;
         } else {
@@ -454,6 +456,7 @@ maybe_t<tok_t> tokenizer_t::tok_next() {
             result.type = TOK_COMMENT;
             result.offset = comment_start - this->start;
             result.length = comment_len;
+            result.preceding_escaped_nl = preceding_escaped_nl;
             return result;
         }
         while (iswspace_not_nl(this->buff[0])) this->buff++;
@@ -551,6 +554,7 @@ maybe_t<tok_t> tokenizer_t::tok_next() {
             break;
         }
     }
+    result.preceding_escaped_nl = preceding_escaped_nl;
     return result;
 }
 

src/tokenizer.h

@@ -82,6 +82,9 @@ struct tok_t {
     // If an error, this is the error code.
     tokenizer_error *error { TOK_ERROR_NONE };
 
+    // Whether the token was preceded by an escaped newline.
+    bool preceding_escaped_nl{false};
+
     // If an error, this is the offset of the error within the token. A value of 0 means it occurred
     // at 'offset'.
     size_t error_offset{size_t(-1)};