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const std = @import("std");
const jv = @import("../jv.zig");
const Instr = @import("./compile.zig").Instr;
pub const ExecuteError = error{
Unimplemented,
InvalidType,
InternalError,
};
pub fn execute(allocator: std.mem.Allocator, instrs: []const Instr, input: jv.Value) !jv.Value {
var value_stack = try std.array_list.Aligned(jv.Value, null).initCapacity(allocator, 16);
defer value_stack.deinit(allocator);
try value_stack.append(allocator, input);
const len = instrs.len;
var pc: usize = 0;
while (pc < len) {
const cur = instrs[pc];
switch (cur) {
.nop => {},
.array_index => {
const v1 = value_stack.pop() orelse return error.InternalError;
const v1_integer = switch (v1) {
.integer => |integer| integer,
else => return error.InvalidType,
};
const v2 = value_stack.pop() orelse return error.InternalError;
const v2_array = switch (v2) {
.array => |array| array,
else => return error.InvalidType,
};
const index: usize = @intCast(v1_integer);
const result = if (index < v2_array.items.len) v2_array.items[index] else .null;
try value_stack.append(allocator, result);
},
.literal => |value| {
try value_stack.append(allocator, value.*);
},
}
pc += 1;
}
const result = value_stack.pop() orelse return error.InternalError;
return result;
}
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