Strings: add toUint, toInt and hexToUint #5166

Amxx · 2024-08-28T09:34:48Z

As discussed. Usefull for parsing addresses from CAIP10 identifier (strings)

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contracts/utils/Strings.sol

.changeset/eighty-hounds-promise.md

cairoeth · 2024-09-02T09:33:10Z

contracts/utils/Strings.sol

+     * @dev Parse an decimal string and returns the value as a `int256`.
+     *
+     * This function will revert if:
+     * - the string contains any character (outside the prefix) that is not in [0-9].
+     * - the result does not fit in a int256.


Suggested change

* @dev Parse an decimal string and returns the value as a `int256`.

*

* This function will revert if:

* - the string contains any character (outside the prefix) that is not in [0-9].

* - the result does not fit in a int256.

* @dev Parse a string in decimal (i.e. base 10) and returns the value as a `int256`.

*

* This function will revert if:

* - the string contains any character (outside the prefix) that is not in [0-9].

* - the result does not fit in a `int256`.

cairoeth · 2024-09-02T09:33:39Z

contracts/utils/Strings.sol

+     * @dev Parse an decimal string and returns the value as a `uint256`.
+     *
+     * This function will revert if:
+     * - the string contains any character that is not in [0-9].
+     * - the result does not fit in a uint256.


Suggested change

* @dev Parse an decimal string and returns the value as a `uint256`.

*

* This function will revert if:

* - the string contains any character that is not in [0-9].

* - the result does not fit in a uint256.

* @dev Parse a string in decimal (i.e. base 10) and returns the value as a `uint256`.

*

* This function will revert if:

* - the string contains any character that is not in [0-9].

* - the result does not fit in a `uint256`.

When looking online, It looks like "decimal string" is the correct way. Maybe "string in decimal format" would be ok, but "string in decimal" doesn't look commonly used.

https://books.google.com/ngrams/graph?content=decimal+string%2Cstring+in+decimal&year_start=1800&year_end=2019&corpus=en-2019&smoothing=0

I'd be fine with decimal string too. I see that's the current state so it's fine imo

contracts/utils/Strings.sol

Co-authored-by: cairo <[email protected]>

contracts/utils/Strings.sol

cairoeth · 2024-09-05T12:55:57Z

contracts/utils/Strings.sol

+    function hexToUint(string memory input) internal pure returns (uint256) {
+        bytes memory buffer = bytes(input);
+
+        // skip 0x prefix if present. Length check doesn't appear to be critical


second sentence feels out of place

Suggested change

// skip 0x prefix if present. Length check doesn't appear to be critical

// skip 0x prefix if present

Just for the record, this is what the comment was about:

The string length may be less than 2. String could be empty, of just "1". In some cases, doing a input[1] or even a input[0] would revert (out of bound acces). Doing bytes2(input) does not revert if the string is to short.

So we check the length to verify that it ok to read the prefix ? It turn out no.

If the string is empty, then regardless of the result of that lookup (that could read dirty bytes), the loop will not run (because length == 0), and the result will be 0 -> that is ok

If the string has length 1 then we have two options

the check identifies the prefix

that means the string is "0", and there is a dirty x after.

In that case we have an offset of 2, and the length is 1, so the for loop does not run and the function returns 0 -> that is ok

the check does not find the prefix

the only "digit" is read by the loop, and the result should be just fine

If the string has length >= 2, then the prefix lookup is in the bounds

That is the long explanation (I'm happy its visible in the PR 😃) to something that is not really trivial, and can be missed, but missing it is not a risk.

We may get questions about it though ...

Co-authored-by: cairo <[email protected]>

TODO: add functions to specify start and end of string to parse

frangio · 2024-09-13T18:54:26Z

contracts/utils/Strings.sol

+    }
+
+    // TODO: documentation.
+    function unsafeReadBytesOffset(bytes memory buffer, uint256 offset) internal pure returns (bytes32 value) {


This is a bytes operation so it shouldn't be in the Strings library.

Where should that go ? A Bytes library ?

Note that the same function exists in RSA.sol

I believe this function was present in other places but always private.

Yes. private, and marked as memory safe, because the private calls are all enforcing the safety.

But we are starting to use it in many places ... so having 3 private implementation of the same functions (with different names?) doesn't feel right.

FYI https://github.com/Amxx/openzeppelin-contracts/pull/5/files

Yes. private, and marked as memory safe, because the private calls are all enforcing the safety.

Right... That was the issue. That using memory-unsafe functions disables some optimizations globally, so they were important to avoid.

So do we want to have:

multiple private (and memory safe) implementations

one internal, none memory safe implementation

one internal, memory safe (checks memory bound) implementation
?

contracts/utils/Strings.sol

ernestognw

I see we added more variations of the base functions and understand that we might want to reduce it. However, I like that the interface is pretty versatile (especially by providing pointers).

I'm not too worried about the length of this particular library since it's not procedurally generated

contracts/utils/Strings.sol

ernestognw · 2024-09-06T19:02:06Z

contracts/utils/Strings.sol

+     * @dev Parse an decimal string and returns the value as a `uint256`.
+     *
+     * This function will revert if:
+     * - the string contains any character that is not in [0-9].
+     * - the result does not fit in a uint256.


I'd be fine with decimal string too. I see that's the current state so it's fine imo

contracts/utils/Strings.sol

Co-authored-by: Ernesto García <[email protected]>

contracts/utils/Strings.sol

Strings: add toUint, toInt and hexToUint

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Amxx requested review from ernestognw and cairoeth August 28, 2024 09:34

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Update .changeset/eighty-hounds-promise.md

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Update Strings.sol

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Update contracts/utils/Strings.sol

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Amxx added 2 commits September 4, 2024 18:13

make return explicit

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branchless

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add try variants + use for governor proposal parsing

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Amxx force-pushed the feature/parse-strings branch from 9c2c8b1 to a7a6e9e Compare September 9, 2024 19:36

parseAddress

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vit870 mentioned this pull request Sep 15, 2024

abstract contract ERC721URIStorage is ERC721 { using Strings for uint256; // Optional mapping for token URIs mapping(uint256 => string) internal _tokenURIs; ... #5202

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Amxx and others added 3 commits September 17, 2024 14:07

use string literal for 0x

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add support for + prefix in parseInt

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Strings: add toUint, toInt and hexToUint #5166

Strings: add toUint, toInt and hexToUint #5166

Amxx commented Aug 28, 2024

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ernestognw Sep 6, 2024

	// skip 0x prefix if present. Length check doesn't appear to be critical
	// skip 0x prefix if present

Strings: add toUint, toInt and hexToUint #5166

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Strings: add toUint, toInt and hexToUint #5166

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Amxx commented Aug 28, 2024

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