# cmake -P CMakeLists.txt
# 变量
set(JOHN_NAME "John Smith")
set(JOHN_ADDRESS "123 Fake St")
set(PERSON "JOHN")
set(${PERSON}_NAME "John Goodman")
message("${${PERSON}_NAME} lives at ${${PERSON}_ADDRESS}.")

# 命令
math(EXPR MY_SUM "1 + 1")                   # Evaluate 1 + 1; store result in MY_SUM
message("The sum is ${MY_SUM}.")
math(EXPR DOUBLE_SUM "${MY_SUM} * 2")       # Multiply by 2; store result in DOUBLE_SUM
message("Double that is ${DOUBLE_SUM}.")

#流程控制
if(WIN32)
    message("You're running CMake on Windows.")
endif()

set(A "1")
set(B "1")
while(A LESS "1000000")
    message("${A}")                 # Print A
    math(EXPR T "${A} + ${B}")      # Add the numeric values of A and B; store result in T
    set(A "${B}")                   # Assign the value of B to A
    set(B "${T}")                   # Assign the value of T to B
endwhile()

foreach(ARG These are separate arguments)
    message("${ARG}")                           # Prints each word on a separate line
endforeach()

foreach(ARG ${MY_LIST})                         # Splits the list; passes items as arguments
    message("${ARG}")                           # Prints each item on a separate line
endforeach()

# 函数
function(doubleIt VARNAME VALUE)
    math(EXPR RESULT "${VALUE} * 2")
    set(${VARNAME} "${RESULT}" PARENT_SCOPE)    # Set the named variable in caller's scope
endfunction()

doubleIt(RESULT "4")                    # Tell the function to set the variable named RESULT
message("${RESULT}")                    # Prints: 8

#宏
macro(doubleIt VARNAME VALUE)
    math(EXPR ${VARNAME} "${VALUE} * 2")        # Set the named variable in caller's scope
endmacro()

doubleIt(RESULT "4")                    # Tell the macro to set the variable named RESULT
message("${RESULT}")                    # Prints: 8

# 未命名的参数用 ARGN 变量获取
function(doubleEach)
    foreach(ARG ${ARGN})                # Iterate over each argument
        math(EXPR N "${ARG} * 2")       # Double ARG's numeric value; store result in N
        message("${N}")                 # Print N
    endforeach()
endfunction()

doubleEach(5 6 7 8)                     # Prints 10, 12, 14, 16 on separate lines

add_executable()
add_library()
add_custom_target()