[Use python self-made programming language] Part 4

Preface

I have done a programming language: mylang

Start

Upload code

def split_subBlocks(block):
    subBlocks = []
    cnt = 0
    buf = ''
    flag = False
    for i in block:
        if(i == '{'):
            cnt += 1
            flag = True
        elif(i == '}'):
            cnt -= 1
            flag = True
        if(cnt == 0 and flag):
            subBlocks.append(buf)
            buf = ''
            flag = False
        else:
            buf += i
    subBlocks[-1] += '}'
    return subBlocks
# ......N行之后......
def parse_if(block):
    subBlocks = split_subBlocks(block)
    if(subBlocks[0] == 'error'):
        return subBlocks
    for i in subBlocks:
        if(i.startswith('if')):
            foo = i.split('\n')[0][3:-2]
        elif(i.startswith('elsif')):
            foo = i.split('\n')[0][6:-2]
        elif(i.startswith('else')):
            foo = 'true'
        else:
            return ['error','IfSentenceError:find undefined branch head']
        code = [j.strip() for j in i.split('\n')[1:-1]]
        F = comp(foo)
        if(F[0] == 'error'):
            return F
        if(F[0]):
            for i in code:
                val = comp(i)
                if(val[0] == 'error'):
                    return val
            return ['']
    return ['']

Parameters
block : code

At the beginning

    subBlocks = split_subBlocks(block)
    if(subBlocks[0] == 'error'):
        return subBlocks

Here separate each block of if, elsif and else, see the code of split_subBlocks:

def split_subBlocks(block):
   subBlocks = []
   cnt = 0
   buf = ''
   flag = False
   for i in block:
       if(i == '{'):
         cnt += 1
           flag = True
       elif(i == '}'):
           cnt -= 1
           flag = True
       if(cnt == 0 and flag):
           subBlocks.append(buf)
           buf = ''
           flag = False
       else:
           buf += i
   subBlocks[-1] += '}'
   return subBlocks

---

first part

def split_subBlocks(block):
   subBlocks = []
   cnt = 0
   buf = ''

Here define variables subBlocks (blocks), cnt (number of brackets to be paired), buf (sentences that have not yet been segmented)

---

---

the second part

for i in block:
       if(i == '{'):
         cnt += 1
           flag = True
       elif(i == '}'):
           cnt -= 1
           flag = True
       if(cnt == 0 and flag):
           subBlocks.append(buf)
           buf = ''
           flag = False
       else:
           buf += i

---

Part II-1

       if(i == '{'):
         cnt += 1
           flag = True
       elif(i == '}'):
           cnt -= 1
           flag = True

Count the number of braces

---

Part 2-2

       if(cnt == 0 and flag):
           subBlocks.append(buf)
           buf = ''
           flag = False

If it can be segmented, segment

---

Part II-3

      else:
          buf += i

If it cannot be segmented, record it as an unsegmented sentence

Behind

    for i in subBlocks:
        if(i.startswith('if')):
            foo = i.split('\n')[0][3:-2]
        elif(i.startswith('elsif')):
            foo = i.split('\n')[0][6:-2]
        elif(i.startswith('else')):
            foo = 'true'
        else:
            return ['error','IfSentenceError:find undefined branch head']

Analyze the head of this paragraph

carry on

        code = [j.strip() for j in i.split('\n')[1:-1]]
        F = comp(foo)
        if(F[0] == 'error'):
            return F
        if(F[0]):
            for i in code:
                val = comp(i)
                if(val[0] == 'error'):
                    return val
            return ['']
    return ['']

The execution procedure
here is based on the previous, it should not be difficult to understand

in conclusion

in conclusion:

>> [Use python self-made programming language] Chapter 5

###### Author hit-road

Bye, get out of class is over!

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