Adding account balance API.

contracts/eoslib/account.h

+/**
+ *  @file
+ *  @copyright defined in eos/LICENSE.txt
+ */
+#pragma once
+
+#include <eoslib/types.h>
+
+/**
+ *  @defgroup accountcapi Account API
+ *  @brief Define API for querying account data
+ *  @ingroup contractdev
+ */
+
+extern "C" {
+   /**
+    * @brief Return the balance for the provided account
+    *
+    * @param balance -  a pointer to a range of memory to store balance data
+    * @param len     -  length of the range of memory to store balance data
+    *
+    * @pre data is a valid pointer to a range of memory at least datalen bytes long
+    * @pre data is a pointer to a balance object
+    * @pre *((uint64_t*)data) stores the primary key
+    *
+    *  Example:
+    *  @code
+    *  balance b;
+    *  b.account = n(myaccount);
+    *  balance(b, sizeof(balance));
+    *  @endcode
+    */
+
+   void account_balance_get( void* balance, uint32_t len );
+   ///@ } accountcapi
+}

contracts/eoslib/account.hpp

+/**
+* @file token.hpp
+* @copyright defined in eos/LICENSE.txt
+* @brief Defines types and ABI for standard token messages and database tables
+*
+*/
+#pragma once
+#include <eoslib/math.hpp>
+#include <eoslib/print.hpp>
+
+
+namespace eosio { namespace account {
+  /**
+  *  @defgroup tokens Token API
+  *  @brief Defines the ABI for interfacing with standard-compatible token messages and database tables.
+  *  @ingroup contractdev
+  *
+  * @{
+  */
+
+/**
+*  @struct eosio::account_balance (must match account_balance defined in wasm_interface.cpp)
+*  @brief The binary structure expected and populated by native balance function.
+*  @ingroup tokens
+*
+*  @details
+*  Example:
+*  @code
+*  account_balance test1_balance;
+*  test1_balance.account = N(test1);
+*  if (account_api::get(test1_balance))
+*  {
+*     eos::print("test1 balance=", test1_balance.eos_balance, "\n");
+*  }
+*  @endcode
+*  @{
+*/
+struct PACKED (account_balance) {
+  /**
+  * Name of the account who's balance this is
+  * @brief Name of the account who's balance this is
+  */
+  account_name account;
+
+  /**
+  * Balance for this account
+  * @brief Balance for this account
+  */
+  asset eos_balance;
+
+  /**
+  * Staked balance for this account
+  * @brief Staked balance for this account
+  */
+  asset staked_balance;
+
+  /**
+  * Unstaking balance for this account
+  * @brief Unstaking balance for this account
+  */
+  asset unstaking_balance;
+
+  /**
+  * Time at which last unstaking occurred for this account
+  * @brief Time at which last unstaking occurred for this account
+  */
+  time last_unstaking_time;
+};
+
+/**
+ *  Retrieve a populated balance structure
+ *  @param account_balance    stream to write
+ *  @ret true if account's balance is found
+ */
+
+bool get(account_balance& b)
+{
+   return account_balance(&b, sizeof(account_balance));
+}
+
+} }

libraries/chain/wasm_interface.cpp

@@ -17,6 +17,8 @@
 #include "IR/Validate.h"
 #include <eos/chain/key_value_object.hpp>
 #include <eos/chain/account_object.hpp>
+#include <eos/chain/balance_object.hpp>
+#include <eos/chain/staked_balance_objects.hpp>
 #include <eos/types/abi_serializer.hpp>
 #include <chrono>
 #include <boost/lexical_cast.hpp>
@@ -46,6 +48,42 @@ namespace eosio { namespace chain {
       U32 _num_bytes;
    };
 
+   // account.h/hpp expected account API balance interchange format
+   // must match account.hpp account_balance definition
+   PACKED_STRUCT(
+   struct account_balance
+   {
+      /**
+      * Name of the account who's balance this is
+      * @brief Name of the account who's balance this is
+      */
+      account_name account;
+
+      /**
+      * Balance for this account
+      * @brief Balance for this account
+      */
+      asset eos_balance;
+
+      /**
+      * Staked balance for this account
+      * @brief Staked balance for this account
+      */
+      asset staked_balance;
+
+      /**
+      * Unstaking balance for this account
+      * @brief Unstaking balance for this account
+      */
+      asset unstaking_balance;
+
+      /**
+      * Time at which last unstaking occurred for this account
+      * @brief Time at which last unstaking occurred for this account
+      */
+      time last_unstaking_time;
+   })
+
    wasm_interface::wasm_interface() {
    }
 
@@ -688,6 +726,30 @@ DEFINE_INTRINSIC_FUNCTION2(env,printhex,printhex,none,i32,data,i32,datalen) {
 DEFINE_INTRINSIC_FUNCTION1(env,free,free,none,i32,ptr) {
 }
 
+DEFINE_INTRINSIC_FUNCTION2(env,account_balance_get,account_balance_get,i32,i32,charptr,i32,len) {
+  auto& wasm  = wasm_interface::get();
+  auto  mem   = wasm.current_memory;
+
+  const uint32_t account_balance_size = sizeof(account_balance);
+  FC_ASSERT( len == account_balance_size, "passed in len ${len} is not equal to the size of an account_balance struct == ${real_len}", ("len",len)("real_len",account_balance_size) );
+
+  account_balance& total_balance = memoryRef<account_balance>( mem, charptr );
+
+  auto& db = wasm.current_apply_context->db;
+  auto* balance        = db.find< balance_object,by_owner_name >( total_balance.account );
+  auto* staked_balance = db.find<staked_balance_object,by_owner_name>( total_balance.account );
+
+  if (balance == nullptr || staked_balance == nullptr)
+     return false;
+
+  total_balance.eos_balance          = asset(balance->balance, EOS_SYMBOL);
+  total_balance.staked_balance       = asset(staked_balance->staked_balance);
+  total_balance.unstaking_balance    = asset(staked_balance->unstaking_balance);
+  total_balance.last_unstaking_time  = staked_balance->last_unstaking_time;
+
+  return true;
+}
+
    wasm_interface& wasm_interface::get() {
       static wasm_interface*  wasm = nullptr;
       if( !wasm )