CP/M/CPM_CDROM.iso/simtel/cpmug/cpmug050.ark/PASYNTAX.DOC

Text File | 1984-04-29 | 5.9 KB | 213 lines

UPPER CASE means that this reserved word must appear literaly.



identifier
------------> letter ------------------------>
            ^          |
            |-- letter <--|
            |-- digit  <--|


number
------------> digit -------->
    ^            |
    |---------------|


constant
-----------> number ---------------------------------------------->
    |                             ^
    |--> constant identifier ----------------------------|
    |               ^              |  |
    |               |-- constant <--  +  --|  |
    |                             |
    |                             |
    |-->  '  --> character -->  '  ----------------------|


simple type
----------------> type identifier ---------------->
    |                       ^
    |-->  (  ----> identifier ----->  )  --|
    |       ^            |           |
    |       |------  ,  <----|           |
    |                       |
    |--> constant -->  ..  --> constant ---|


type
----------------> simple type -------------------------------->
    |                        ^
    |--> ARRAY -->  [  --> simple type -->  ] --|   |
                            |   |
       |----------------------------------------|   |
       |                        |
       |--> OF --> simple type ---------------------|


variable
------------> variable identifier ---------------------------->
                    |      |
    |---------------------------|      |
    |                  |
    |-->  [  --> expression -->  ]  --|


factor
------------>  '  -----> character ----->  '  ---------------->
    |        ^             |            |
    |        |----------------|            |
    |                        |
    |--> variable --------------------------------->|
    |                        |
    |--> function identifier ---------------------->|
    |               |            |
    |  |-----------------------|            |
    |  |                        |
    |  |-->  (  -----> expression ----->  )  ------>|
    |          ^            |        |
    |          |-----  ,  <------|        |
    |                        |
    |-->  (  --> expression -->  )  --------------->|
    |                        |
    |--> constant ----------------------------------|


term
------------> factor -------------------------------->
    ^             |
    |-- factor <-----  *  <--|
              ^         |
              |--  /  <--|
              |-- AND <--|

simple expression
----------->  +  -------> term -------------------------------->
    |       ^ ^                |
    |-->  -  --| |-- term <-----  +  <--|
                 ^        |
                 |--  -  <--|
                 |--  OR <--|


expression
-----------> simple expression -------------------------------------->
                |                    ^
                |-->  =  -----> simple expression --|
                |       ^
                |-->  <  --|
                |-->  >  --|
                |-->  <> --|
                |-->  <= --|
                |-->  >= --|


parameter list
-------------------------------------------------------------------------->
 |                                  |
 |--> ( -----> identifier -----> : --> type identifier -----> ) --|
     ^ ^            |                 |
     | |-----  ,  <-----|                 |
     |                         |
     |-----------------------  ;  <------------------|



statement
--------------------------------------------------------------------->
 |                                  ^
 |-----> variable ---------------->  :=  --> expression --------->|
 |  |                   ^                  |
 |  |--> function identifier --|                  |
 |                                  |
 |--> procedure identifier -------------------------------------->|
 |                 |                      |
 |  |<-----------------------|                      |
 |  |                                  |
 |  |-->  (  ------------------> expression ----->  )  ---------->|
 |           |      ^ ^              |              |
 |           |--> VAR --| |------  ,  <-----|              |
 |                                  |
 |--> BEGIN -----> statement -----> END ------------------------->|
 |          ^               |                  |
 |          |-----  ;  <-----|                  |
 |                                  |
 |--> IF --> expression --> THEN --> statement ------------------>|
 |                             |          |
 |                       |<--------|          |
 |                       |              |
 |                       |--> ELSE --> statement -->|
 |                                  |
 |--> CASE --> expression --> OF ------------------------> END -->|
 |                   |              ^          |
 |  |<-----------------------------|              |          |
 |  |                                |          |
 |  |-----> constant --> : --> statement ------------>|          |
 |     ^                   | |          |          |
 |     |---------------  ;  ---------------| |        |          |
 |                         |        |          |
 |        |<---------------------------|        |          |
 |        |                      |          |
 |        |--> ELSE --> statement ------------->|          |
 |                                  |
 |--> WHILE --> expression --> DO --> statement ----------------->|
 |                                  |
 |--> REPEAT -----> statement -----> UNTIL --> expression ------->|
 |           ^        |                  |
 |           |-----  ;  <-----|                  |
 |                                  |
 |--> GET -->  #  --> constant -->  (  --> variable -->  )  ----->|
 |                                  |
 |--> PUT -->  #  --> constant -->  (  --|              |
 |                     |              |
 |           |<--------------------|              |
 |           |                          |
 |           |-----> expression ------------------->  )  -->|
 |              ^            |       ^  |          |
 |              |            |-->  #  --|  |          |
 |              |                      |          |
 |              |----------  ,  <---------------|          |
 |                                  |
 |--> FOR --> variable identifier -->  :=  --> expression --|      |
                                |      |
     |<-------------------------------------------------|      |
     |                              |
     |-----> DOWNTO -----> expression --> DO --> statement -->|
        |          ^
        |----> TO ----|


block
-----------> CONST -----> identifier -->  =  --> constant --|
    |         ^                        |
    |         |                        |
    |<-------------------------------------  ;  <-------|
    |
    |--> TYPE ------> identifier -->  =  --> type ------|
    |         ^                        |
    |         |                        |
    |<-------------------------------------  ;  <-------|
    |
    |--> VAR -------> identifier ----->  :  --> type identifier ---|
    |         ^               |                       |
    |         |<-----  ,  ------|                       |
    |         ^                                   |
    |<-------------------------------------------------------------|
    |
    |<-----  ;  <----- block <-----  ;  <--------------------|
    |                             |
    |-----> procedure -----> identifier --> parameter list --|
    |  |            ^
    |  |--> function ---|
    |
    |--> begin -----> statement -----> end -------------------->
             ^              |
             |-----  ;  <-----|


program
------------> block -->  .  ---------------------------------------->