core: support parsing back slash \ in parseKey in FileStorage (JSON)
#27587
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@fengyuentau What about raw strings in python with triple quotes? |
@asmorkalov Thank you for suggestion! Now it works as expected with the # a.json: {"\"":1,"\\":59,"Ġ\"":366,"\\\\":6852}
import cv2 as cv
import json
# a.json
a = cv.FileStorage("a.json", cv.FileStorage_FORMAT_JSON)
print(type(a), a.getNode("\"").real(), a.getNode(r"\\").real())
# <class 'cv2.FileStorage'> 1.0 59.0
with open("a.json", "r") as f:
a = json.load(f)
print(type(a), a["\""], a["\\"])
# <class 'dict'> 1 59 |
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@dkurt @asmorkalov I found multiple sources saying that backslash should be escaped as well. So python's json printing a key of double backslash should be the reason of human readability; that's to say in memory it is still parsed as one single backslash # a.json: {"\"":1,"\\":59,"Ġ\"":366,"\\\\":6852}
import json
with open("a.json", "r") as f:
a = json.load(f)
print(a.keys())
# dict_keys(['"', '\\', 'Ġ"', '\\\\'])
print(type(a), a["\""], a["\\"], a[r"\\"])
# <class 'dict'> 1 59 6852What do you think? |
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With the latest commit, we can do the following things correctly: import cv2 as cv
import json
# a.json
a = cv.FileStorage("a.json", cv.FileStorage_FORMAT_JSON)
print(a.getNode("\"").name(), a.getNode("\\").name(), a.getNode(r"\\").name())
# " \ \\
print(type(a), a.getNode("\"").real(), a.getNode("\\").real(), a.getNode(r"\\").real())
# <class 'cv2.FileStorage'> 1.0 59.0 6852.0
with open("a.json", "r") as f:
a = json.load(f)
print(a.keys())
# dict_keys(['"', '\\', 'Ġ"', '\\\\'])
print(type(a), a["\""], a["\\"], a[r"\\"])
# <class 'dict'> 1 59 6852
# tokenizer.json
a = cv.FileStorage("tokenizer.json", cv.FileStorage_FORMAT_JSON)
b = a.getNode("model")
c = b.getNode("vocab")
print(type(a), c.getNode("\"").real(), c.getNode("\\").real())
# <class 'cv2.FileStorage'> 1.0 59.0
with open("tokenizer.json", "r") as f:
a = json.load(f)
b = a["model"]
c = b["vocab"]
print(type(a), c["\""], c["\\"])
# <class 'dict'> 1 59The only problem now is our key does not show as python's json's. I guess it is fine since it is different way to show information. |
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I would say, that it's the case, when real file on opencv_extra is better than hard-coded solution. It's error prone and with file with do not need to re-check escape sequences and other syntax sugar in particular programming language. |
The current test uses raw string; that should be clear enough for readability and maintainability. |
Fixes #27585
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See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
Patch to opencv_extra has the same branch name.