ethers.js/utils/abi-coder.js

'use strict';

// See: https://github.com/ethereum/wiki/wiki/Ethereum-Contract-ABI

var throwError = require('../utils/throw-error');

var utils = (function() {
    var convert = require('../utils/convert.js');
    var utf8 = require('../utils/utf8.js');

    return {
        defineProperty: require('../utils/properties.js').defineProperty,

        arrayify: convert.arrayify,
        padZeros: convert.padZeros,

        bigNumberify: require('../utils/bignumber.js').bigNumberify,

        getAddress: require('../utils/address').getAddress,

        concat: convert.concat,

        toUtf8Bytes: utf8.toUtf8Bytes,
        toUtf8String: utf8.toUtf8String,

        hexlify: convert.hexlify,
    };
})();

var paramTypeBytes = new RegExp(/^bytes([0-9]*)$/);
var paramTypeNumber = new RegExp(/^(u?int)([0-9]*)$/);
var paramTypeArray = new RegExp(/^(.*)\[([0-9]*)\]$/);

var defaultCoerceFunc = function(type, value) {
    var match = type.match(paramTypeNumber)
    if (match && parseInt(match[2]) <= 48) { return value.toNumber(); }
    return value;
}

var coderNull = function(coerceFunc) {
    return {
        name: 'null',
        type: '',
        encode: function(value) {
            return utils.arrayify([]);
        },
        decode: function(data, offset) {
            if (offset > data.length) { throw new Error('invalid null'); }
            return {
                consumed: 0,
                value: coerceFunc('null', undefined)
            }
        },
        dynamic: false
    };
}

var coderNumber = function(coerceFunc, size, signed, localName) {
    var name = ((signed ? 'int': 'uint') + (size * 8));
    return {
        localName: localName,
        name: name,
        type: name,
        encode: function(value) {
            value = utils.bigNumberify(value).toTwos(size * 8).maskn(size * 8);
            //value = value.toTwos(size * 8).maskn(size * 8);
            if (signed) {
                value = value.fromTwos(size * 8).toTwos(256);
            }
            return utils.padZeros(utils.arrayify(value), 32);
        },
        decode: function(data, offset) {
            if (data.length < offset + 32) { throwError('invalid ' + name); }
            var junkLength = 32 - size;
            var value = utils.bigNumberify(data.slice(offset + junkLength, offset + 32));
            if (signed) {
                value = value.fromTwos(size * 8);
            } else {
                value = value.maskn(size * 8);
            }

            //if (size <= 6) { value = value.toNumber(); }

            return {
                consumed: 32,
                value: coerceFunc(name, value),
            }
        }
    };
}
var uint256Coder = coderNumber(function(type, value) { return value; }, 32, false);

var coderBoolean = function(coerceFunc, localName) {
    return {
        localName: localName,
        name: 'boolean',
        type: 'boolean',
        encode: function(value) {
           return uint256Coder.encode(value ? 1: 0);
        },
       decode: function(data, offset) {
            try {
                var result = uint256Coder.decode(data, offset);
            } catch (error) {
                if (error.message === 'invalid uint256') {
                    throwError('invalid bool');
                }
                throw error;
            }
            return {
                consumed: result.consumed,
                value: coerceFunc('boolean', !result.value.isZero())
            }
        }
    }
}

var coderFixedBytes = function(coerceFunc, length, localName) {
    var name = ('bytes' + length);
    return {
        localName: localName,
        name: name,
        type: name,
        encode: function(value) {
            value = utils.arrayify(value);
            if (length === 32) { return value; }

            var result = new Uint8Array(32);
            result.set(value);
            return result;
        },
        decode: function(data, offset) {
            if (data.length < offset + 32) { throwError('invalid bytes' + length); }

            return {
                consumed: 32,
                value: coerceFunc(name, utils.hexlify(data.slice(offset, offset + length)))
            }
        }
    };
}

var coderAddress = function(coerceFunc, localName) {
    return {
        localName: localName,
        name: 'address',
        type: 'address',
        encode: function(value) {
            value = utils.arrayify(utils.getAddress(value));
            var result = new Uint8Array(32);
            result.set(value, 12);
            return result;
        },
        decode: function(data, offset) {
            if (data.length < offset + 32) { throwError('invalid address'); }
            return {
                consumed: 32,
                value: coerceFunc('address', utils.getAddress(utils.hexlify(data.slice(offset + 12, offset + 32))))
           }
        }
    }
}

function _encodeDynamicBytes(value) {
    var dataLength = parseInt(32 * Math.ceil(value.length / 32));
    var padding = new Uint8Array(dataLength - value.length);

    return utils.concat([
        uint256Coder.encode(value.length),
        value,
        padding
    ]);
}

function _decodeDynamicBytes(data, offset) {
    if (data.length < offset + 32) { throwError('invalid bytes'); }

    var length = uint256Coder.decode(data, offset).value;
    length = length.toNumber();
    if (data.length < offset + 32 + length) { throwError('invalid bytes'); }

    return {
        consumed: parseInt(32 + 32 * Math.ceil(length / 32)),
        value: data.slice(offset + 32, offset + 32 + length),
    }
}

var coderDynamicBytes = function(coerceFunc, localName) {
    return {
        localName: localName,
        name: 'bytes',
        type: 'bytes',
        encode: function(value) {
            return _encodeDynamicBytes(utils.arrayify(value));
        },
        decode: function(data, offset) {
            var result = _decodeDynamicBytes(data, offset);
            result.value = coerceFunc('bytes', utils.hexlify(result.value));
            return result;
        },
        dynamic: true
    };
}

var coderString = function(coerceFunc, localName) {
    return {
        localName: localName,
        name: 'string',
        type: 'string',
        encode: function(value) {
            return _encodeDynamicBytes(utils.toUtf8Bytes(value));
        },
        decode: function(data, offset) {
            var result = _decodeDynamicBytes(data, offset);
            result.value = coerceFunc('string', utils.toUtf8String(result.value));
            return result;
        },
        dynamic: true
    };
}

function alignSize(size) {
    return parseInt(32 * Math.ceil(size / 32));
}

function pack(coders, values) {
    if (Array.isArray(values)) {
        if (coders.length !== values.length) {
            throwError('types/values mismatch', { type: type, values: values });
        }

    } else if (values && typeof(values) === 'object') {
        var arrayValues = [];
        coders.forEach(function(coder) {
            arrayValues.push(values[coder.localName]);
        });
        values = arrayValues;

    } else {
        throwError('invalid value', { type: 'tuple', values: values });
    }

    var parts = [];

    coders.forEach(function(coder, index) {
        parts.push({ dynamic: coder.dynamic, value: coder.encode(values[index]) });
    });

    var staticSize = 0, dynamicSize = 0;
    parts.forEach(function(part, index) {
        if (part.dynamic) {
            staticSize += 32;
            dynamicSize += alignSize(part.value.length);
        } else {
            staticSize += alignSize(part.value.length);
        }
    });

    var offset = 0, dynamicOffset = staticSize;
    var data = new Uint8Array(staticSize + dynamicSize);

    parts.forEach(function(part, index) {
        if (part.dynamic) {
            //uint256Coder.encode(dynamicOffset).copy(data, offset);
            data.set(uint256Coder.encode(dynamicOffset), offset);
            offset += 32;

            //part.value.copy(data, dynamicOffset);  @TODO
            data.set(part.value, dynamicOffset);
            dynamicOffset += alignSize(part.value.length);
        } else {
            //part.value.copy(data, offset);  @TODO
            data.set(part.value, offset);
            offset += alignSize(part.value.length);
        }
    });

    return data;
}

function unpack(coders, data, offset) {
    var baseOffset = offset;
    var consumed = 0;
    var value = [];
    coders.forEach(function(coder) {
        if (coder.dynamic) {
            var dynamicOffset = uint256Coder.decode(data, offset);
            var result = coder.decode(data, baseOffset + dynamicOffset.value.toNumber());
            // The dynamic part is leap-frogged somewhere else; doesn't count towards size
            result.consumed = dynamicOffset.consumed;
        } else {
            var result = coder.decode(data, offset);
        }

        if (result.value != undefined) {
            value.push(result.value);
        }

        offset += result.consumed;
        consumed += result.consumed;
    });

    coders.forEach(function(coder, index) {
        var name = coder.localName;
        if (!name) { return; }

        if (typeof(name) === 'object') { name = name.name; }
        if (!name) { return; }

        if (name === 'length') { name = '_length'; }

        if (value[name] != null) { return; }

        value[name] = value[index];
    });

    return {
        value: value,
        consumed: consumed
    }

    return result;
}

function coderArray(coerceFunc, coder, length, localName) {
    var type = (coder.type + '[' + (length >= 0 ? length: '') + ']');

    return {
        coder: coder,
        localName: localName,
        length: length,
        name: 'array',
        type: type,
        encode: function(value) {
            if (!Array.isArray(value)) { throwError('invalid array'); }

            var count = length;

            var result = new Uint8Array(0);
            if (count === -1) {
                count = value.length;
                result = uint256Coder.encode(count);
            }

            if (count !== value.length) { throwError('size mismatch'); }

            var coders = [];
            value.forEach(function(value) { coders.push(coder); });

            return utils.concat([result, pack(coders, value)]);
        },
        decode: function(data, offset) {
            // @TODO:
            //if (data.length < offset + length * 32) { throw new Error('invalid array'); }

            var consumed = 0;

            var count = length;

            if (count === -1) {
                 var decodedLength = uint256Coder.decode(data, offset);
                 count = decodedLength.value.toNumber();
                 consumed += decodedLength.consumed;
                 offset += decodedLength.consumed;
            }

            var coders = [];
            for (var i = 0; i < count; i++) { coders.push(coder); }

            var result = unpack(coders, data, offset);
            result.consumed += consumed;
            result.value = coerceFunc(type, result.value);
            return result;
        },
        dynamic: (length === -1 || coder.dynamic)
    }
}


function coderTuple(coerceFunc, coders, localName) {
    var dynamic = false;
    var types = [];
    coders.forEach(function(coder) {
        if (coder.dynamic) { dynamic = true; }
        types.push(coder.type);
    });

    var type = ('tuple(' + types.join(',') + ')');

    return {
        coders: coders,
        localName: localName,
        name: 'tuple',
        type: type,
        encode: function(value) {
            return pack(coders, value);
        },
        decode: function(data, offset) {
            var result = unpack(coders, data, offset);
            result.value = coerceFunc(type, result.value);
            return result;
        },
        dynamic: dynamic
    };
}
/*
function getTypes(coders) {
    var type = coderTuple(coders).type;
    return type.substring(6, type.length - 1);
}
*/
function splitNesting(value) {
    var result = [];
    var accum = '';
    var depth = 0;
    for (var offset = 0; offset < value.length; offset++) {
        var c = value[offset];
        if (c === ',' && depth === 0) {
            result.push(accum);
            accum = '';
        } else {
            accum += c;
            if (c === '(') {
                depth++;
            } else if (c === ')') {
                depth--;
                if (depth === -1) {
                    throw new Error('unbalanced parenthsis');
                }
            }
        }
    }
    result.push(accum);

    return result;
}

var paramTypeSimple = {
    address: coderAddress,
    bool: coderBoolean,
    string: coderString,
    bytes: coderDynamicBytes,
};

function getParamCoder(coerceFunc, type, localName) {
    var coder = paramTypeSimple[type];
    if (coder) { return coder(coerceFunc, localName); }

    var match = type.match(paramTypeNumber);
    if (match) {
        var size = parseInt(match[2] || 256);
        if (size === 0 || size > 256 || (size % 8) !== 0) {
            throwError('invalid type', { type: type });
        }
        return coderNumber(coerceFunc, size / 8, (match[1] === 'int'), localName);
    }

    var match = type.match(paramTypeBytes);
    if (match) {
        var size = parseInt(match[1]);
        if (size === 0 || size > 32) {
            throwError('invalid type ' + type);
        }
        return coderFixedBytes(coerceFunc, size, localName);
    }

    var match = type.match(paramTypeArray);
    if (match) {
        var size = parseInt(match[2] || -1);
        return coderArray(coerceFunc, getParamCoder(coerceFunc, match[1], localName), size, localName);
    }

    if (type.substring(0, 6) === 'tuple(' && type.substring(type.length - 1) === ')') {
        var coders = [];
        var names = [];
        if (localName && typeof(localName) === 'object') {
            if (Array.isArray(localName.names)) { names = localName.names; }
            if (typeof(localName.name) === 'string') { localName = localName.name; }
        }
        splitNesting(type.substring(6, type.length - 1)).forEach(function(type, index) {
            coders.push(getParamCoder(coerceFunc, type, names[index]));
        });
        return coderTuple(coerceFunc, coders, localName);
    }

    if (type === '') {
        return coderNull(coerceFunc);
    }

    throwError('invalid type', { type: type });
}

function Coder(coerceFunc) {
    if (!(this instanceof Coder)) { throw new Error('missing new'); }
    if (!coerceFunc) { coerceFunc = defaultCoerceFunc; }
    utils.defineProperty(this, 'coerceFunc', coerceFunc);
}

utils.defineProperty(Coder.prototype, 'encode', function(names, types, values) {

    // Names is optional, so shift over all the parameters if not provided
    if (arguments.length < 3) {
        values = types;
        types = names;
        names = null;
    }

    if (types.length !== values.length) { throwError('types/values mismatch', {types: types, values: values}); }

    var coders = [];
    types.forEach(function(type, index) {
        coders.push(getParamCoder(this.coerceFunc, type, (names ? names[index]: undefined)));
    }, this);

    return utils.hexlify(coderTuple(this.coerceFunc, coders).encode(values));
});

utils.defineProperty(Coder.prototype, 'decode', function(names, types, data) {

    // Names is optional, so shift over all the parameters if not provided
    if (arguments.length < 3) {
        data = types;
        types = names;
        names = null;
    }

    data = utils.arrayify(data);

    var coders = [];
    types.forEach(function(type, index) {
        coders.push(getParamCoder(this.coerceFunc, type, (names ? names[index]: undefined)));
    }, this);

    return coderTuple(this.coerceFunc, coders).decode(data, 0).value;

});

utils.defineProperty(Coder, 'defaultCoder', new Coder());

module.exports = Coder