     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60

    //! Some transaction validation rules,
    //! require sophisticated (in more than one source) previous transaction lookups

    use chain::{OutPoint, TransactionOutput};
    use network::TransactionOrdering;
    use storage::TransactionOutputProvider;

    #[derive(Clone, Copy)]
    pub struct DuplexTransactionOutputProvider<'a> {
    	first: &'a TransactionOutputProvider,
    	second: &'a TransactionOutputProvider,
    }

    impl<'a> DuplexTransactionOutputProvider<'a> {
    	pub fn new(first: &'a TransactionOutputProvider, second: &'a TransactionOutputProvider) -> Self {
    		DuplexTransactionOutputProvider {
    			first: first,
    			second: second,
    		}
    	}
    }

    impl<'a> TransactionOutputProvider for DuplexTransactionOutputProvider<'a> {
    	fn transaction_output(&self, prevout: &OutPoint, transaction_index: usize) -> Option<TransactionOutput> {
    		self.first.transaction_output(prevout, transaction_index)
    			.or_else(|| self.second.transaction_output(prevout, transaction_index))
    	}

    	fn is_spent(&self, prevout: &OutPoint) -> bool {
    		self.first.is_spent(prevout) || self.second.is_spent(prevout)
    	}
    }

    pub struct NoopStore;

    impl TransactionOutputProvider for NoopStore {
    	fn transaction_output(&self, _prevout: &OutPoint, _transaction_index: usize) -> Option<TransactionOutput> {
    		None
    	}

    	fn is_spent(&self, _prevout: &OutPoint) -> bool {
    		false
    	}
    }

    /// Converts actual transaction index into transaction index to use in
    /// TransactionOutputProvider::transaction_output call.
    /// When topological ordering is used, we expect ascendant transaction (TX1)
    /// to come BEFORE descendant transaction (TX2) in the block, like this:
    /// [ ... TX1 ... TX2 ... ]
    /// When canonical ordering is used, transactions order within block is not
    /// relevant for this check and ascendant transaction (TX1) can come AFTER
    /// descendant, like this:
    /// [ ... TX2 ... TX1 ... ]
    pub fn transaction_index_for_output_check(ordering: TransactionOrdering, tx_idx: usize) -> usize {
    	match ordering {
    		TransactionOrdering::Topological => tx_idx,
    		TransactionOrdering::Canonical => ::std::usize::MAX,
    	}
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g. `str,u8` or `String,struct:Vec,test`)