update jq differences to clarify regular expression differences

README.md

@@ -77,8 +77,8 @@ docker run -i --rm ghcr.io/itchyny/gojq
 - gojq implements nice error messages for invalid query and JSON input. The error message of jq is sometimes difficult to tell where to fix the query.
 - gojq does not keep the order of object keys. I understand this might cause problems for some scripts but basically, we should not rely on the order of object keys. Due to this limitation, gojq does not have `keys_unsorted` function and `--sort-keys` (`-S`) option. I would implement when ordered map is implemented in the standard library of Go but I'm less motivated.
 - gojq supports arbitrary-precision integer calculation while jq does not; jq loses the precision of large integers when calculation is involved. Note that even with gojq, all mathematical functions, including `floor` and `round`, convert integers to floating-point numbers; only addition, subtraction, multiplication, modulo, and division operators (when divisible) keep the integer precision. To calculate floor division of integers without losing the precision, use `def idivide($n): (. - . % $n) / $n;`. To round down floating-point numbers to integers, use `def ifloor: floor | tostring | tonumber;`, but note that this function does not work with large floating-point numbers and also loses the precision of large integers.
-- gojq behaves differently than jq in some features, hoping that jq will fix the behaviors in the future. gojq consistently counts by characters (not by bytes) in `index`, `rindex`, and `indices` functions; `"１２３４５" | .[index("３"):]` results in `"３４５"` ([jq#1430](https://github.com/jqlang/jq/issues/1430), [jq#1624](https://github.com/jqlang/jq/issues/1624)). gojq supports string indexing; `"abcde"[2]` ([jq#1520](https://github.com/jqlang/jq/issues/1520)). gojq fixes handling files with no newline characters at the end ([jq#2374](https://github.com/jqlang/jq/issues/2374)). gojq consistently truncates down floating-point number indices both in indexing (`[0] | .[0.5]` results in `0`), and slicing (`[0,1,2] | .[0.5:1.5]` results in `[0]`). gojq parses unary operators with higher precedence than variable binding (`[-1 as $x | 1,$x]` results in `[1,-1]` not `[-1,-1]`). gojq fixes `@base64d` to allow binary string as the decoded string ([jq#1931](https://github.com/jqlang/jq/issues/1931)). gojq improves time formatting and parsing; deals with `%f` in `strftime` and `strptime` ([jq#1409](https://github.com/jqlang/jq/issues/1409)), parses timezone offsets with `fromdate` and `fromdateiso8601` ([jq#1053](https://github.com/jqlang/jq/issues/1053)), supports timezone name/offset with `%Z`/`%z` in `strptime` ([jq#929](https://github.com/jqlang/jq/issues/929), [jq#2195](https://github.com/jqlang/jq/issues/2195)), and looks up correct timezone during daylight saving time on formatting with `%Z` ([jq#1912](https://github.com/jqlang/jq/issues/1912)). gojq supports nanoseconds in date and time functions.
-- gojq does not support some functions intentionally; `get_jq_origin`, `get_prog_origin`, `get_search_list` (unstable, not listed in jq document), `input_line_number`, `$__loc__` (performance issue), `recurse_down` (deprecated in jq). gojq does not support some flags; `--ascii-output, -a` (performance issue), `--seq` (not used commonly), `--sort-keys, -S` (sorts by default because `map[string]any` does not keep the order), `--unbuffered` (unbuffered by default). gojq does not parse JSON extensions supported by jq; `NaN`, `Infinity`, and `[000]`. gojq normalizes floating-point numbers to fit to double-precision floating-point numbers. gojq does not support or behaves differently with some regular expression metacharacters and flags (regular expression engine differences). gojq does not support BOM (`encoding/json` does not support this). gojq disallows using keywords for function names (`def true: .; true` is a confusing query), and module name prefixes in function declarations (using module prefixes like `def m::f: .;` is undocumented).
+- gojq behaves differently than jq in some features, hoping that jq will fix the behaviors in the future. gojq consistently counts by characters (not by bytes) in `index`, `rindex`, and `indices` functions; `"１２３４５" | .[index("３"):]` results in `"３４５"` ([jq#1430](https://github.com/jqlang/jq/issues/1430), [jq#1624](https://github.com/jqlang/jq/issues/1624)). gojq supports string indexing; `"abcde"[2]` ([jq#1520](https://github.com/jqlang/jq/issues/1520)). gojq fixes handling files with no newline characters at the end ([jq#2374](https://github.com/jqlang/jq/issues/2374)). gojq consistently truncates down floating-point number indices both in indexing (`[0] | .[0.5]` results in `0`), and slicing (`[0,1,2] | .[0.5:1.5]` results in `[0]`). gojq parses unary operators with higher precedence than variable binding (`[-1 as $x | 1,$x]` results in `[1,-1]` not `[-1,-1]`) ([jq#3053](https://github.com/jqlang/jq/pull/3053)). gojq fixes `@base64d` to allow binary string as the decoded string ([jq#1931](https://github.com/jqlang/jq/issues/1931)). gojq improves time formatting and parsing; deals with `%f` in `strftime` and `strptime` ([jq#1409](https://github.com/jqlang/jq/issues/1409)), parses timezone offsets with `fromdate` and `fromdateiso8601` ([jq#1053](https://github.com/jqlang/jq/issues/1053)), supports timezone name/offset with `%Z`/`%z` in `strptime` ([jq#929](https://github.com/jqlang/jq/issues/929), [jq#2195](https://github.com/jqlang/jq/issues/2195)), and looks up correct timezone during daylight saving time on formatting with `%Z` ([jq#1912](https://github.com/jqlang/jq/issues/1912)). gojq supports nanoseconds in date and time functions.
+- gojq does not support some functions intentionally; `get_jq_origin`, `get_prog_origin`, `get_search_list` (unstable, not listed in jq document), `input_line_number`, `$__loc__` (performance issue). gojq does not support some flags; `--ascii-output, -a` (performance issue), `--seq` (not used commonly), `--sort-keys, -S` (sorts by default because `map[string]any` does not keep the order), `--unbuffered` (unbuffered by default). gojq does not parse JSON extensions supported by jq; `NaN`, `Infinity`, and `[000]`. gojq normalizes floating-point numbers to fit to double-precision floating-point numbers. gojq does not support some regular expression metacharacters, backreferences, look-around assertions, and some flags (regular expression engine differences). gojq does not support BOM (`encoding/json` does not support this). gojq disallows using keywords for function names (`def true: .; true` is a confusing query), and module name prefixes in function declarations (using module prefixes like `def m::f: .;` is undocumented).
 - gojq supports reading from YAML input (`--yaml-input`) while jq does not. gojq also supports YAML output (`--yaml-output`). gojq supports `@urid` format string ([jq#798](https://github.com/jqlang/jq/issues/798), [jq#2261](https://github.com/jqlang/jq/issues/2261)).
 
 ### Color configuration
@@ -154,7 +154,7 @@ func main() {
 Report bug at [Issues・itchyny/gojq - GitHub](https://github.com/itchyny/gojq/issues).
 
 ## Author
-itchyny (https://github.com/itchyny)
+itchyny (<https://github.com/itchyny>)
 
 ## License
 This software is released under the MIT License, see LICENSE.