Create a docgen tool

[nlachfr]

Add a small utility for generating the list of standard definitions of the specification.
The added descriptions comes directly from the current specification.

Output example (with markdown formatting) :

These descriptions are automatically generated based on the cel-go implementation.

Symbol	Type	Description
!_	(bool) -> bool	logical not
-_	(int) -> int	negation
	(double) -> double	negation
_!=_	(A, A) -> bool	inequality
_%_	(int, int) -> int	arithmetic
	(uint, uint) -> uint	arithmetic
_&&_	(bool, bool) -> bool	logical and
_*_	(int, int) -> int	arithmetic
	(uint, uint) -> uint	arithmetic
	(double, double) -> double	arithmetic
_+_	(int, int) -> int	arithmetic
	(uint, uint) -> uint	arithmetic
	(double, double) -> double	arithmetic
	(string, string) -> string	string concatenation. Space and time cost proportional to the sum of the input sizes.
	(bytes, bytes) -> bytes	bytes concatenation
	(list(A), list(A)) -> list(A)	list concatenation. Space and time cost proportional to the sum of the input sizes.
	(google.protobuf.Timestamp, google.protobuf.Duration) -> google.protobuf.Timestamp	arithmetic
	(google.protobuf.Duration, google.protobuf.Timestamp) -> google.protobuf.Timestamp	arithmetic
	(google.protobuf.Duration, google.protobuf.Duration) -> google.protobuf.Duration	arithmetic
_-_	(int, int) -> int	arithmetic
	(uint, uint) -> uint	arithmetic
	(double, double) -> double	arithmetic
	(google.protobuf.Timestamp, google.protobuf.Timestamp) -> google.protobuf.Duration	arithmetic
	(google.protobuf.Timestamp, google.protobuf.Duration) -> google.protobuf.Timestamp	arithmetic
	(google.protobuf.Duration, google.protobuf.Duration) -> google.protobuf.Duration	arithmetic
_/_	(int, int) -> int	arithmetic
	(uint, uint) -> uint	arithmetic
	(double, double) -> double	arithmetic
_<=_	(bool, bool) -> bool	ordering
	(int, int) -> bool	ordering
	(int, double) -> bool	ordering
	(int, uint) -> bool	ordering
	(uint, uint) -> bool	ordering
	(uint, double) -> bool	ordering
	(uint, int) -> bool	ordering
	(double, double) -> bool	ordering
	(double, int) -> bool	ordering
	(double, uint) -> bool	ordering
	(string, string) -> bool	ordering
	(bytes, bytes) -> bool	ordering
	(google.protobuf.Timestamp, google.protobuf.Timestamp) -> bool	ordering
	(google.protobuf.Duration, google.protobuf.Duration) -> bool	ordering
_<_	(bool, bool) -> bool	ordering
	(int, int) -> bool	ordering
	(int, double) -> bool	ordering
	(int, uint) -> bool	ordering
	(uint, uint) -> bool	ordering
	(uint, double) -> bool	ordering
	(uint, int) -> bool	ordering
	(double, double) -> bool	ordering
	(double, int) -> bool	ordering
	(double, uint) -> bool	ordering
	(string, string) -> bool	ordering
	(bytes, bytes) -> bool	ordering
	(google.protobuf.Timestamp, google.protobuf.Timestamp) -> bool	ordering
	(google.protobuf.Duration, google.protobuf.Duration) -> bool	ordering
_==_	(A, A) -> bool	equality
_>=_	(bool, bool) -> bool	ordering
	(int, int) -> bool	ordering
	(int, double) -> bool	ordering
	(int, uint) -> bool	ordering
	(uint, uint) -> bool	ordering
	(uint, double) -> bool	ordering
	(uint, int) -> bool	ordering
	(double, double) -> bool	ordering
	(double, int) -> bool	ordering
	(double, uint) -> bool	ordering
	(string, string) -> bool	ordering
	(bytes, bytes) -> bool	ordering
	(google.protobuf.Timestamp, google.protobuf.Timestamp) -> bool	ordering
	(google.protobuf.Duration, google.protobuf.Duration) -> bool	ordering
_>_	(bool, bool) -> bool	ordering
	(int, int) -> bool	ordering
	(int, double) -> bool	ordering
	(int, uint) -> bool	ordering
	(uint, uint) -> bool	ordering
	(uint, double) -> bool	ordering
	(uint, int) -> bool	ordering
	(double, double) -> bool	ordering
	(double, int) -> bool	ordering
	(double, uint) -> bool	ordering
	(string, string) -> bool	ordering
	(bytes, bytes) -> bool	ordering
	(google.protobuf.Timestamp, google.protobuf.Timestamp) -> bool	ordering
	(google.protobuf.Duration, google.protobuf.Duration) -> bool	ordering
_?_:_	(bool, A, A) -> A	The conditional operator. See above for evaluation semantics. Will evaluate the test and only one of the remaining sub-expressions.
_[_]	(list(A), int) -> A	list indexing. Constant time cost.
	(map(A, B), A) -> B	map indexing. For string keys, cost is proportional to the size of the map keys times the size of the index string.
_||_	(bool, bool) -> bool	logical or
bool	type(bool)	type denotation
	(bool) -> bool	type conversion
	(string) -> bool	type conversion
bytes	type(bytes)	type denotation
	(bytes) -> bytes	type conversion
	(string) -> bytes	type conversion
contains	string.(string) -> bool	Tests whether the string operand contains the substring. Time cost proportional to the product of sizes of the arguments.
double	type(double)	type denotation
	(double) -> double	type conversion
	(int) -> double	type conversion
	(uint) -> double	type conversion
	(string) -> double	type conversion
duration	(google.protobuf.Duration) -> google.protobuf.Duration	type conversion
	(string) -> google.protobuf.Duration	Type conversion. Duration strings should support the following suffixes: "h" (hour), "m" (minute), "s" (second), "ms" (millisecond), "us" (microsecond), and "ns" (nanosecond). Duration strings may be zero, negative, fractional, and/or compound. Examples: "0", "-1.5h", "1m6s"
	(int) -> google.protobuf.Duration	type conversion
dyn	(A) -> dyn	type conversion
endsWith	string.(string) -> bool	Tests whether the string operand ends with the suffix argument. Time cost proportional to the product of the sizes of the arguments.
getDate	google.protobuf.Timestamp.() -> int	get day of month from the date in UTC, one-based indexing
	google.protobuf.Timestamp.(string) -> int	get day of month from the date with timezone, one-based indexing
getDayOfMonth	google.protobuf.Timestamp.() -> int	get day of month from the date in UTC, zero-based indexing
	google.protobuf.Timestamp.(string) -> int	get day of month from the date with timezone, zero-based indexing
getDayOfWeek	google.protobuf.Timestamp.() -> int	get day of week from the date in UTC, zero-based, zero for Sunday
	google.protobuf.Timestamp.(string) -> int	get day of week from the date with timezone, zero-based, zero for Sunday
getDayOfYear	google.protobuf.Timestamp.() -> int	get day of year from the date in UTC, zero-based indexing
	google.protobuf.Timestamp.(string) -> int	get day of year from the date with timezone, zero-based indexing
getFullYear	google.protobuf.Timestamp.() -> int	get year from the date in UTC
	google.protobuf.Timestamp.(string) -> int	get year from the date with timezone
getHours	google.protobuf.Timestamp.() -> int	get hours from the date in UTC, 0-23
	google.protobuf.Timestamp.(string) -> int	get hours from the date with timezone, 0-23
	google.protobuf.Duration.() -> int	get hours from duration
getMilliseconds	google.protobuf.Timestamp.() -> int	get milliseconds from the date in UTC, 0-999
	google.protobuf.Timestamp.(string) -> int	get milliseconds from the date with timezone, 0-999
	google.protobuf.Duration.() -> int	milliseconds from duration, 0-999
getMinutes	google.protobuf.Timestamp.() -> int	get minutes from the date in UTC, 0-59
	google.protobuf.Timestamp.(string) -> int	get minutes from the date with timezone, 0-59
	google.protobuf.Duration.() -> int	get minutes from duration
getMonth	google.protobuf.Timestamp.() -> int	get month from the date in UTC, 0-11
	google.protobuf.Timestamp.(string) -> int	get month from the date with timezone, 0-11
getSeconds	google.protobuf.Timestamp.() -> int	get seconds from the date in UTC, 0-59
	google.protobuf.Timestamp.(string) -> int	get seconds from the date with timezone, 0-59
	google.protobuf.Duration.() -> int	get seconds from duration
in	(A, list(A)) -> bool	list membership. Time cost proportional to the product of the size of both arguments.
	(A, map(A, B)) -> bool	map key membership. Time cost proportional to the product of the size of both arguments.
int	type(int)	type denotation
	(int) -> int	type conversion
	(uint) -> int	type conversion
	(double) -> int	Type conversion. Rounds toward zero, then errors if result is out of range.
	(string) -> int	type conversion
	(google.protobuf.Timestamp) -> int	type conversion
	(google.protobuf.Duration) -> int	Convert timestamp to int64 in seconds since Unix epoch.
list	type(list(A))	type denotation
map	type(map(A, B))	type denotation
matches	(string, string) -> bool	Matches first argument against regular expression in second argument. Time cost proportional to the product of the sizes of the arguments.
	string.(string) -> bool	Matches the self argument against regular expression in first argument. Time cost proportional to the product of the sizes of the arguments.
null_type	type(null)	type denotation
size	string.() -> int	string size
	bytes.() -> int	length size
	list(A).() -> int	list size. Time cost proportional to the length of the list.
	map(A, B).() -> int	map size. Time cost proportional to the number of entries.
	(string) -> int	string length
	(bytes) -> int	bytes length
	(list(A)) -> int	list size. Time cost proportional to the length of the list.
	(map(A, B)) -> int	map size. Time cost proportional to the number of entries.
startsWith	string.(string) -> bool	Tests whether the string operand starts with the prefix argument. Time cost proportional to the product of the sizes of the arguments.
string	type(string)	type denotation
	(string) -> string	type conversion
	(bool) -> string	type conversion
	(int) -> string	type conversion
	(uint) -> string	type conversion
	(double) -> string	type conversion
	(bytes) -> string	type conversion
	(google.protobuf.Timestamp) -> string	type conversion, using the same format as timestamp string parsing
	(google.protobuf.Duration) -> string	type conversion, using the same format as duration string parsing
timestamp	(google.protobuf.Timestamp) -> google.protobuf.Timestamp	type conversion
	(string) -> google.protobuf.Timestamp	Type conversion of strings to timestamps according to RFC3339. Example: "1972-01-01T10:00:20.021-05:00"
	(int) -> google.protobuf.Timestamp	type conversion
type	type(dyn)	type denotation
	(A) -> type(A)	returns type of value
uint	type(uint)	type denotation
	(uint) -> uint	type conversion
	(int) -> uint	type conversion
	(double) -> uint	Type conversion. Rounds toward zero, then errors if result is out of range.
	(string) -> uint	type conversion

Resolves #9

[TristonianJones]

/gcbrun