+/* Returns the offset of the current token within the command being parsed in
+ LEXER. This is 0 for the first token in a command, 1 for the second, and so
+ on. The return value is useful later for referring to this token in calls
+ to lex_ofs_*(). */
+int
+lex_ofs (const struct lexer *lexer)
+{
+ struct lex_source *src = lex_source__ (lexer);
+ return src ? src->parse_ofs : 0;
+}
+
+/* Returns the token within LEXER's current command with offset OFS. Use
+ lex_ofs() to find out the offset of the current token. */
+const struct token *
+lex_ofs_token (const struct lexer *lexer_, int ofs)
+{
+ struct lexer *lexer = CONST_CAST (struct lexer *, lexer_);
+ struct lex_source *src = lex_source__ (lexer);
+
+ if (src != NULL)
+ return &lex_source_next__ (src, ofs - src->parse_ofs)->token;
+ else
+ {
+ static const struct token stop_token = { .type = T_STOP };
+ return &stop_token;
+ }
+}
+
+/* Allocates and returns a new struct msg_location that spans tokens with
+ offsets OFS0 through OFS1, inclusive, within the current command in
+ LEXER. See lex_ofs() for an explanation of token offsets.
+
+ The caller owns and must eventually free the returned object. */
+struct msg_location *
+lex_ofs_location (const struct lexer *lexer, int ofs0, int ofs1)
+{
+ int ofs = lex_ofs (lexer);
+ return lex_get_location (lexer, ofs0 - ofs, ofs1 - ofs);
+}
+
+/* Returns a msg_point for the first character in the token with offset OFS,
+ where offset 0 is the first token in the command currently being parsed, 1
+ the second token, and so on. These are absolute offsets, not relative to
+ the token currently being parsed within the command.
+
+ Returns zeros for a T_STOP token.
+ */
+struct msg_point
+lex_ofs_start_point (const struct lexer *lexer, int ofs)
+{
+ const struct lex_source *src = lex_source__ (lexer);
+ return (src
+ ? lex_token_start_point (src, lex_source_ofs__ (src, ofs))
+ : (struct msg_point) { 0, 0 });
+}
+
+/* Returns a msg_point for the last character, inclusive, in the token with
+ offset OFS, where offset 0 is the first token in the command currently being
+ parsed, 1 the second token, and so on. These are absolute offsets, not
+ relative to the token currently being parsed within the command.
+
+ Returns zeros for a T_STOP token.
+
+ Most of the time, a single token is wholly within a single line of syntax,
+ so that the start and end point for a given offset have the same line
+ number. There are two exceptions: a T_STRING token can be made up of
+ multiple segments on adjacent lines connected with "+" punctuators, and a
+ T_NEG_NUM token can consist of a "-" on one line followed by the number on
+ the next.
+ */
+struct msg_point
+lex_ofs_end_point (const struct lexer *lexer, int ofs)
+{
+ const struct lex_source *src = lex_source__ (lexer);
+ return (src
+ ? lex_token_end_point (src, lex_source_ofs__ (src, ofs))
+ : (struct msg_point) { 0, 0 });
+}
+