Arithmetic evaluation: Difference between revisions

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@@ Line 1,346: / Line 1,346: @@
 .
 subr init0
-   a$[] = [ ]
+   astop$[] = [ ]
-   ale[] = [ ]
+   astleft[] = [ ]
-   ari[] = [ ]
+   astright[] = [ ]
    err = 0
 .
@@ Line 1,359: / Line 1,359: @@
 .
 proc ast_print nd . .
-   write "AST: " & nd
+   write "AST:"
-   for i to len a$[]
+   for i to len astop$[]
       write " ( "
-      write a$[i] & " "
+      write astop$[i] & " "
-      write ale[i] & " "
+      write astleft[i] & " "
-      write ari[i]
+      write astright[i]
       write " )"
    .
-   print ""
+   print " Start: " & nd
 .
 func node .
-   a$[] &= ""
+   astop$[] &= ""
-   ale[] &= 0
+   astleft[] &= 0
-   ari[] &= 0
+   astright[] &= 0
-   return len a$[]
+   return len astop$[]
 .
 #
@@ Line 1,381: / Line 1,381: @@
    if tok$ = "n"
       nd = node
-      a$[nd] = "n"
+      astop$[nd] = "n"
-      ale[nd] = tokv
+      astleft[nd] = tokv
       ntok
    elif tok$ = "("
@@ Line 1,399: / Line 1,399: @@
    while tok$ = "*" or tok$ = "/"
       nd = node
-      ale[nd] = ndx
+      astleft[nd] = ndx
-      a$[nd] = tok$
+      astop$[nd] = tok$
       ntok
-      ari[nd] = parse_factor
+      astright[nd] = parse_factor
       ndx = nd
    .
@@ Line 1,411: / Line 1,411: @@
    while tok$ = "+" or tok$ = "-"
       nd = node
-      ale[nd] = ndx
+      astleft[nd] = ndx
-      a$[nd] = tok$
+      astop$[nd] = tok$
       ntok
-      ari[nd] = parse_term
+      astright[nd] = parse_term
       ndx = nd
    .
@@ Line 1,424: / Line 1,424: @@
 .
 func eval nd .
-   if a$[nd] = "n"
+   if astop$[nd] = "n"
-      return ale[nd]
+      return astleft[nd]
    .
-   le = eval ale[nd]
+   le = eval astleft[nd]
-   ri = eval ari[nd]
+   ri = eval astright[nd]
-   a$ = a$[nd]
+   a$ = astop$[nd]
    if a$ = "+"
       return le + ri
@@ Line 1,454: / Line 1,454: @@
 * 6
 .2 * ((5.3+8)*3 + 4)
 .5 * 2 + 2 * 3.14
 </syntaxhighlight>