+
+## ----------------- ##
+## GNU pic Grammar. ##
+## ----------------- ##
+
+AT_SETUP([GNU pic Grammar])
+
+# GNU pic, part of groff.
+
+# Bison once reported shift/reduce conflicts that it shouldn't have.
+
+AT_DATA([[input.y]],
+[[%union {}
+
+%token LABEL
+%token VARIABLE
+%token NUMBER
+%token TEXT
+%token COMMAND_LINE
+%token DELIMITED
+%token ORDINAL
+%token TH
+%token LEFT_ARROW_HEAD
+%token RIGHT_ARROW_HEAD
+%token DOUBLE_ARROW_HEAD
+%token LAST
+%token UP
+%token DOWN
+%token LEFT
+%token RIGHT
+%token BOX
+%token CIRCLE
+%token ELLIPSE
+%token ARC
+%token LINE
+%token ARROW
+%token MOVE
+%token SPLINE
+%token HEIGHT
+%token RADIUS
+%token WIDTH
+%token DIAMETER
+%token FROM
+%token TO
+%token AT
+%token WITH
+%token BY
+%token THEN
+%token SOLID
+%token DOTTED
+%token DASHED
+%token CHOP
+%token SAME
+%token INVISIBLE
+%token LJUST
+%token RJUST
+%token ABOVE
+%token BELOW
+%token OF
+%token THE
+%token WAY
+%token BETWEEN
+%token AND
+%token HERE
+%token DOT_N
+%token DOT_E
+%token DOT_W
+%token DOT_S
+%token DOT_NE
+%token DOT_SE
+%token DOT_NW
+%token DOT_SW
+%token DOT_C
+%token DOT_START
+%token DOT_END
+%token DOT_X
+%token DOT_Y
+%token DOT_HT
+%token DOT_WID
+%token DOT_RAD
+%token SIN
+%token COS
+%token ATAN2
+%token LOG
+%token EXP
+%token SQRT
+%token K_MAX
+%token K_MIN
+%token INT
+%token RAND
+%token SRAND
+%token COPY
+%token THRU
+%token TOP
+%token BOTTOM
+%token UPPER
+%token LOWER
+%token SH
+%token PRINT
+%token CW
+%token CCW
+%token FOR
+%token DO
+%token IF
+%token ELSE
+%token ANDAND
+%token OROR
+%token NOTEQUAL
+%token EQUALEQUAL
+%token LESSEQUAL
+%token GREATEREQUAL
+%token LEFT_CORNER
+%token RIGHT_CORNER
+%token NORTH
+%token SOUTH
+%token EAST
+%token WEST
+%token CENTER
+%token END
+%token START
+%token RESET
+%token UNTIL
+%token PLOT
+%token THICKNESS
+%token FILL
+%token COLORED
+%token OUTLINED
+%token SHADED
+%token ALIGNED
+%token SPRINTF
+%token COMMAND
+
+%left '.'
+
+/* this ensures that plot 17 "%g" parses as (plot 17 "%g") */
+%left PLOT
+%left TEXT SPRINTF
+
+/* give text adjustments higher precedence than TEXT, so that
+box "foo" above ljust == box ("foo" above ljust)
+*/
+
+%left LJUST RJUST ABOVE BELOW
+
+%left LEFT RIGHT
+/* Give attributes that take an optional expression a higher
+precedence than left and right, so that eg `line chop left'
+parses properly. */
+%left CHOP SOLID DASHED DOTTED UP DOWN FILL COLORED OUTLINED
+%left LABEL
+
+%left VARIABLE NUMBER '(' SIN COS ATAN2 LOG EXP SQRT K_MAX K_MIN INT RAND SRAND LAST
+%left ORDINAL HERE '`'
+
+%left BOX CIRCLE ELLIPSE ARC LINE ARROW SPLINE '[' /* ] */
+
+/* these need to be lower than '-' */
+%left HEIGHT RADIUS WIDTH DIAMETER FROM TO AT THICKNESS
+
+/* these must have higher precedence than CHOP so that `label %prec CHOP'
+works */
+%left DOT_N DOT_E DOT_W DOT_S DOT_NE DOT_SE DOT_NW DOT_SW DOT_C
+%left DOT_START DOT_END TOP BOTTOM LEFT_CORNER RIGHT_CORNER
+%left UPPER LOWER NORTH SOUTH EAST WEST CENTER START END
+
+%left ','
+%left OROR
+%left ANDAND
+%left EQUALEQUAL NOTEQUAL
+%left '<' '>' LESSEQUAL GREATEREQUAL
+
+%left BETWEEN OF
+%left AND
+
+%left '+' '-'
+%left '*' '/' '%'
+%right '!'
+%right '^'
+
+%%
+
+top:
+ optional_separator
+ | element_list
+ ;
+
+element_list:
+ optional_separator middle_element_list optional_separator
+ ;
+
+middle_element_list:
+ element
+ | middle_element_list separator element
+ ;
+
+optional_separator:
+ /* empty */
+ | separator
+ ;
+
+separator:
+ ';'
+ | separator ';'
+ ;
+
+placeless_element:
+ VARIABLE '=' any_expr
+ | VARIABLE ':' '=' any_expr
+ | UP
+ | DOWN
+ | LEFT
+ | RIGHT
+ | COMMAND_LINE
+ | COMMAND print_args
+ | PRINT print_args
+ | SH
+ {}
+ DELIMITED
+ | COPY TEXT
+ | COPY TEXT THRU
+ {}
+ DELIMITED
+ {}
+ until
+ | COPY THRU
+ {}
+ DELIMITED
+ {}
+ until
+ | FOR VARIABLE '=' expr TO expr optional_by DO
+ {}
+ DELIMITED
+ | simple_if
+ | simple_if ELSE
+ {}
+ DELIMITED
+ | reset_variables
+ | RESET
+ ;
+
+reset_variables:
+ RESET VARIABLE
+ | reset_variables VARIABLE
+ | reset_variables ',' VARIABLE
+ ;
+
+print_args:
+ print_arg
+ | print_args print_arg
+ ;
+
+print_arg:
+ expr %prec ','
+ | text
+ | position %prec ','
+ ;
+
+simple_if:
+ IF any_expr THEN
+ {}
+ DELIMITED
+ ;
+
+until:
+ /* empty */
+ | UNTIL TEXT
+ ;
+
+any_expr:
+ expr
+ | text_expr
+ ;
+
+text_expr:
+ text EQUALEQUAL text
+ | text NOTEQUAL text
+ | text_expr ANDAND text_expr
+ | text_expr ANDAND expr
+ | expr ANDAND text_expr
+ | text_expr OROR text_expr
+ | text_expr OROR expr
+ | expr OROR text_expr
+ | '!' text_expr
+ ;
+
+optional_by:
+ /* empty */
+ | BY expr
+ | BY '*' expr
+ ;
+
+element:
+ object_spec
+ | LABEL ':' optional_separator element
+ | LABEL ':' optional_separator position_not_place
+ | LABEL ':' optional_separator place
+ | '{' {} element_list '}'
+ {}
+ optional_element
+ | placeless_element
+ ;
+
+optional_element:
+ /* empty */
+ | element
+ ;
+
+object_spec:
+ BOX
+ | CIRCLE
+ | ELLIPSE
+ | ARC
+ | LINE
+ | ARROW
+ | MOVE
+ | SPLINE
+ | text %prec TEXT
+ | PLOT expr
+ | PLOT expr text
+ | '['
+ {}
+ element_list ']'
+ | object_spec HEIGHT expr
+ | object_spec RADIUS expr
+ | object_spec WIDTH expr
+ | object_spec DIAMETER expr
+ | object_spec expr %prec HEIGHT
+ | object_spec UP
+ | object_spec UP expr
+ | object_spec DOWN
+ | object_spec DOWN expr
+ | object_spec RIGHT
+ | object_spec RIGHT expr
+ | object_spec LEFT
+ | object_spec LEFT expr
+ | object_spec FROM position
+ | object_spec TO position
+ | object_spec AT position
+ | object_spec WITH path
+ | object_spec WITH position %prec ','
+ | object_spec BY expr_pair
+ | object_spec THEN
+ | object_spec SOLID
+ | object_spec DOTTED
+ | object_spec DOTTED expr
+ | object_spec DASHED
+ | object_spec DASHED expr
+ | object_spec FILL
+ | object_spec FILL expr
+ | object_spec SHADED text
+ | object_spec COLORED text
+ | object_spec OUTLINED text
+ | object_spec CHOP
+ | object_spec CHOP expr
+ | object_spec SAME
+ | object_spec INVISIBLE
+ | object_spec LEFT_ARROW_HEAD
+ | object_spec RIGHT_ARROW_HEAD
+ | object_spec DOUBLE_ARROW_HEAD
+ | object_spec CW
+ | object_spec CCW
+ | object_spec text %prec TEXT
+ | object_spec LJUST
+ | object_spec RJUST
+ | object_spec ABOVE
+ | object_spec BELOW
+ | object_spec THICKNESS expr
+ | object_spec ALIGNED
+ ;
+
+text:
+ TEXT
+ | SPRINTF '(' TEXT sprintf_args ')'
+ ;
+
+sprintf_args:
+ /* empty */
+ | sprintf_args ',' expr
+ ;
+
+position:
+ position_not_place
+ | place
+ ;
+
+position_not_place:
+ expr_pair
+ | position '+' expr_pair
+ | position '-' expr_pair
+ | '(' position ',' position ')'
+ | expr between position AND position
+ | expr '<' position ',' position '>'
+ ;
+
+between:
+ BETWEEN
+ | OF THE WAY BETWEEN
+ ;
+
+expr_pair:
+ expr ',' expr
+ | '(' expr_pair ')'
+ ;
+
+place:
+ /* line at A left == line (at A) left */
+ label %prec CHOP
+ | label corner
+ | corner label
+ | corner OF label
+ | HERE
+ ;
+
+label:
+ LABEL
+ | nth_primitive
+ | label '.' LABEL
+ ;
+
+ordinal:
+ ORDINAL
+ | '`' any_expr TH
+ ;
+
+optional_ordinal_last:
+ LAST
+ | ordinal LAST
+ ;
+
+nth_primitive:
+ ordinal object_type
+ | optional_ordinal_last object_type
+ ;
+
+object_type:
+ BOX
+ | CIRCLE
+ | ELLIPSE
+ | ARC
+ | LINE
+ | ARROW
+ | SPLINE
+ | '[' ']'
+ | TEXT
+ ;
+
+label_path:
+ '.' LABEL
+ | label_path '.' LABEL
+ ;
+
+relative_path:
+ corner %prec CHOP
+ /* give this a lower precedence than LEFT and RIGHT so that
+ [A: box] with .A left == [A: box] with (.A left) */
+ | label_path %prec TEXT
+ | label_path corner
+ ;
+
+path:
+ relative_path
+ | '(' relative_path ',' relative_path ')'
+ {}
+ /* The rest of these rules are a compatibility sop. */
+ | ORDINAL LAST object_type relative_path
+ | LAST object_type relative_path
+ | ORDINAL object_type relative_path
+ | LABEL relative_path
+ ;
+
+corner:
+ DOT_N
+ | DOT_E
+ | DOT_W
+ | DOT_S
+ | DOT_NE
+ | DOT_SE
+ | DOT_NW
+ | DOT_SW
+ | DOT_C
+ | DOT_START
+ | DOT_END
+ | TOP
+ | BOTTOM
+ | LEFT
+ | RIGHT
+ | UPPER LEFT
+ | LOWER LEFT
+ | UPPER RIGHT
+ | LOWER RIGHT
+ | LEFT_CORNER
+ | RIGHT_CORNER
+ | UPPER LEFT_CORNER
+ | LOWER LEFT_CORNER
+ | UPPER RIGHT_CORNER
+ | LOWER RIGHT_CORNER
+ | NORTH
+ | SOUTH
+ | EAST
+ | WEST
+ | CENTER
+ | START
+ | END
+ ;
+
+expr:
+ VARIABLE
+ | NUMBER
+ | place DOT_X
+ | place DOT_Y
+ | place DOT_HT
+ | place DOT_WID
+ | place DOT_RAD
+ | expr '+' expr
+ | expr '-' expr
+ | expr '*' expr
+ | expr '/' expr
+ | expr '%' expr
+ | expr '^' expr
+ | '-' expr %prec '!'
+ | '(' any_expr ')'
+ | SIN '(' any_expr ')'
+ | COS '(' any_expr ')'
+ | ATAN2 '(' any_expr ',' any_expr ')'
+ | LOG '(' any_expr ')'
+ | EXP '(' any_expr ')'
+ | SQRT '(' any_expr ')'
+ | K_MAX '(' any_expr ',' any_expr ')'
+ | K_MIN '(' any_expr ',' any_expr ')'
+ | INT '(' any_expr ')'
+ | RAND '(' any_expr ')'
+ | RAND '(' ')'
+ | SRAND '(' any_expr ')'
+ | expr '<' expr
+ | expr LESSEQUAL expr
+ | expr '>' expr
+ | expr GREATEREQUAL expr
+ | expr EQUALEQUAL expr
+ | expr NOTEQUAL expr
+ | expr ANDAND expr
+ | expr OROR expr
+ | '!' expr
+ ;
+]])
+
+# Pass plenty of options, to exercise plenty of code, even if we
+# don't actually check the output. But SEGV is watching us, and
+# so might do dmalloc.
+AT_BISON_CHECK([[--verbose --defines input.y]], 0, [],
+[[input.y:453.11-48: warning: rule useless in parser due to conflicts: path: ORDINAL LAST object_type relative_path
+]])
+
+AT_CLEANUP