[Cyan]<Cedar6.0>Tioga>GetTreeImpl.mesa!2

GetTreeImpl.mesa

written by Paxton. May 1981

Paxton. August 24, 1982 10:39 am

Russ Atkinson, July 26, 1983 5:43 pm

Doug Wyatt, March 3, 1985 6:32:00 pm PST

Each line of input file becomes a node (parent for line is the closest previous line with smaller indent).

DIRECTORY

Ascii USING [CR, SP, TAB],

GetTree,

TextNode,

Rope,

RopeEdit,

RopeIO,

RopeReader;

GetTreeImpl: CEDAR PROGRAM

IMPORTS TextNode, RopeEdit, RopeIO, RopeReader

EXPORTS GetTree

= BEGIN OPEN GetTree;

ROPE: TYPE = Rope.ROPE;

Offset: TYPE = TextNode.Offset;

ReadIndent: PUBLIC PROC [fileName: ROPE, tabIndent: NAT ← 4] RETURNS [root: RefTextNode] = {

input: ROPE ← RopeIO.FromFile[fileName];

rdr: RopeReader.Ref ← RopeReader.GetRopeReader[];

maxOpen: NAT = 40;

openNodes: ARRAY [0..maxOpen] OF RefTextNode;

openIndents: ARRAY [0..maxOpen] OF INTEGER;

level, lvl: NAT;

indent: INTEGER;

node: RefTextNode;

noMoreInput: BOOL ← FALSE;

ReadLine: PROC RETURNS [ROPE] = { -- read line and set indent

tab: CHAR=Ascii.TAB;

space: CHAR=Ascii.SP;

cr: CHAR=Ascii.CR;

start, end: Offset ← 0;

indent ← 0;

DO SELECT RopeReader.Get[rdr ! RopeReader.ReadOffEnd => {

noMoreInput ← TRUE; EXIT }] FROM

cr => EXIT; -- blank line

tab => indent ← indent+tabIndent;

space => indent ← indent+1;

0C => { noMoreInput ← TRUE; EXIT }; -- stop at first NULL char

ENDCASE => { -- just saw the first nonblank char on the line

start ← RopeReader.GetIndex[rdr]-1;

DO SELECT RopeReader.Get[rdr ! RopeReader.ReadOffEnd => {

end ← RopeReader.GetIndex[rdr]; noMoreInput ← TRUE; EXIT }] FROM

cr => { end ← RopeReader.GetIndex[rdr]-1; EXIT };

0C => { end ← RopeReader.GetIndex[rdr]-1; noMoreInput ← TRUE; EXIT };

ENDCASE;

ENDLOOP;

EXIT };

ENDLOOP;

RETURN [RopeEdit.Substr[input,start,end-start]] };

PlaceNode: PROC = {

dest: RefTextNode;

SELECT lvl FROM

< level => { -- insert as sibling of node at lvl+1

dest ← openNodes[level ← lvl+1];

dest.last ← FALSE; node.next ← dest.next; dest.next ← node };

= maxOpen => { -- insert as sibling of node at max level

dest ← openNodes[level]; dest.last ← FALSE;

node.next ← dest.next; dest.next ← node };

ENDCASE => { -- increase level

dest ← openNodes[level]; node.next ← dest; dest.child ← node;

level ← level+1 };

node.last ← TRUE; openIndents[level] ← indent; openNodes[level] ← node };

RopeReader.SetPosition[rdr,input,0];

openNodes[0] ← root ← TextNode.NewTextNode[];

root.last ← TRUE;

openIndents[0] ← -1; level ← 0;

UNTIL noMoreInput DO

node ← TextNode.NewTextNode[];

IF (node.rope ← ReadLine[])=NIL THEN indent ← MAX[0,openIndents[level]];

FOR lvl ← level, lvl-1 DO

IF openIndents[lvl] < indent THEN { PlaceNode[]; EXIT };

ENDLOOP;

RopeReader.FreeRopeReader[rdr];

};

END.