Update docs

scripts/generate/templates/SafeCast.js

@@ -0,0 +1,126 @@
+const format = require('../format-lines');
+const { range } = require('../../helpers');
+
+const LENGTHS = range(8, 256, 8).reverse(); // 248 → 8 (in steps of 8)
+
+const header = `\
+pragma solidity ^0.8.20;
+
+/**
+ * @dev Wrappers over Solidity's uintXX/intXX casting operators with added overflow
+ * checks.
+ *
+ * Downcasting from uint256/int256 in Solidity does not revert on overflow. This can
+ * easily result in undesired exploitation or bugs, since developers usually
+ * assume that overflows raise errors. \`SafeCast\` restores this intuition by
+ * reverting the transaction when such an operation overflows.
+ *
+ * Using this library instead of the unchecked operations eliminates an entire
+ * class of bugs, so it's recommended to use it always.
+ */
+`;
+
+const errors = `\
+  /**
+   * @dev Value doesn't fit in an uint of \`bits\` size.
+   */
+  error SafeCastOverflowedUintDowncast(uint8 bits, uint256 value);
+  
+  /**
+   * @dev An int value doesn't fit in an uint of \`bits\` size.
+   */
+  error SafeCastOverflowedIntToUint(int256 value);
+  
+  /**
+   * @dev Value doesn't fit in an int of \`bits\` size.
+   */
+  error SafeCastOverflowedIntDowncast(uint8 bits, int256 value);
+  
+  /**
+   * @dev An uint value doesn't fit in an int of \`bits\` size.
+   */
+  error SafeCastOverflowedUintToInt(uint256 value);
+`;
+
+const toUintDownCast = length => `\
+/**
+ * @dev Returns the downcasted uint${length} from uint256, reverting on
+ * overflow (when the input is greater than largest uint${length}).
+ *
+ * Counterpart to Solidity's \`uint${length}\` operator.
+ *
+ * Requirements:
+ *
+ * - input must fit into ${length} bits
+ */
+function toUint${length}(uint256 value) internal pure returns (uint${length}) {
+    if (value > type(uint${length}).max) {
+      revert SafeCastOverflowedUintDowncast(${length}, value);
+    }
+    return uint${length}(value);
+}
+`;
+
+/* eslint-disable max-len */
+const toIntDownCast = length => `\
+/**
+ * @dev Returns the downcasted int${length} from int256, reverting on
+ * overflow (when the input is less than smallest int${length} or
+ * greater than largest int${length}).
+ *
+ * Counterpart to Solidity's \`int${length}\` operator.
+ *
+ * Requirements:
+ *
+ * - input must fit into ${length} bits
+ */
+function toInt${length}(int256 value) internal pure returns (int${length} downcasted) {
+    downcasted = int${length}(value);
+    if (downcasted != value) {
+      revert SafeCastOverflowedIntDowncast(${length}, value);
+    }
+}
+`;
+/* eslint-enable max-len */
+
+const toInt = length => `\
+/**
+ * @dev Converts an unsigned uint${length} into a signed int${length}.
+ *
+ * Requirements:
+ *
+ * - input must be less than or equal to maxInt${length}.
+ */
+function toInt${length}(uint${length} value) internal pure returns (int${length}) {
+    // Note: Unsafe cast below is okay because \`type(int${length}).max\` is guaranteed to be positive
+    if (value > uint${length}(type(int${length}).max)) {
+      revert SafeCastOverflowedUintToInt(value);
+    }
+    return int${length}(value);
+}
+`;
+
+const toUint = length => `\
+/**
+ * @dev Converts a signed int${length} into an unsigned uint${length}.
+ *
+ * Requirements:
+ *
+ * - input must be greater than or equal to 0.
+ */
+function toUint${length}(int${length} value) internal pure returns (uint${length}) {
+    if (value < 0) {
+      revert SafeCastOverflowedIntToUint(value);
+    }
+    return uint${length}(value);
+}
+`;
+
+// GENERATE
+module.exports = format(
+  header.trimEnd(),
+  'library SafeCast {',
+  errors,
+  [...LENGTHS.map(toUintDownCast), toUint(256), ...LENGTHS.map(toIntDownCast), toInt(256)],
+  '}',
+);