first iteration of method body parser

This commit is contained in:
Dave Holoway
2020-05-18 13:10:45 +01:00
parent 79bba76b9f
commit 66cee87685

View File

@@ -0,0 +1,429 @@
const Token = require('./parsetypes/token');
const Declaration = require('./parsetypes/declaration');
const TypeIdent = require('./parsetypes/typeident');
const { parse_expression, ExpressionText, ParsedExpression } = require('../../src/expression/parse');
class LocalVariableDeclaration extends Declaration {
/**
* @param {*[]} modifiers
* @param {TypeIdent} typeident
*/
constructor(modifiers, typeident) {
super(null, null, modifiers);
this.typeident = typeident;
/** @type {LocalVariable[]} */
this.vars = [];
}
}
class LocalVariable {
/**
* @param {LocalVariableDeclaration} declaration
* @param {Token} name
* @param {Token} arrdims
*/
constructor(declaration, name, arrdims) {
this.declaration = declaration;
this.name = name;
this.arrdims = arrdims;
/** @type {Token} */
this.equals = null;
/** @type {ParsedExpression} */
this.expression = null;
/** @type {Token} */
this.comma = null;
}
}
/**
* @param {string} text
* @param {number} index
*/
function extractExpression(text, index = 0) {
const e = new ExpressionText(text.slice(index));
const parsed = parse_expression(e);
console.log(parsed);
let consumed = text.indexOf(e.expr);
return {
parsed,
index: consumed,
}
}
/**
* Parse a method body
*
* The parser is an inside-out parser.
* It works by tokenizing at the lowest level (comments, whitespace, identifiers, literals and symbols)
* and works its way outward, grouping tokens together in larger and larger chunks that it recognises.
*
* Each stage is forgiving on what it accepts and syntax errors (unexpected or missing tokens) are noted along the way.
* The final parse stage matches a set of statements - the highest-level concept of a method body.
*
* Once the parse is complete, all the complete expressions in the body can be type-resolved and checked.
*
* @param {string} text
* @param {number} text_index
*/
function parseBody(text, text_index = 0) {
const tokens = new TextBlockArray('body');
// preprocess - strip any comments and normalise strings
text = text.replace(/(\/\/.*|\/\*[\D\d]*?\*\/)|(".+?")/g, (_,comment,str) =>
str ?
`"${' '.repeat(str.length-2)}"`
: _.replace(/[^\r\n]/g,' ')
);
const re = /(\s+)|(["'\d]|\b(?:true|false|null)\b)|\b(if|switch|while|else|for|case|default|do|try|finally|catch|return|break|continue)\b|(\bnew\b)|(\w+)|([;{}():])|(.)/g;
for (let m; m = re.exec(text);) {
if (m[1]) {
// ignore ws + comments
continue;
}
if (m[2]) {
// string, character, number, boolean or null literal - parse as an expression
const { parsed, index } = extractExpression(text, m.index);
tokens.blocks.push(new ParsedExpressionBlock(text, m.index, index - m.index, parsed));
re.lastIndex = index;
continue;
}
if (m[3]) {
// statement keyword
tokens.blocks.push(TextBlock.from(text, m.index, m[0].length));
continue;
}
if (m[4]) {
// new keyword - need extra handling because of anonymous types
const { parsed, index } = extractExpression(text, m.index);
tokens.blocks.push(new ParsedExpressionBlock(text, m.index, index - m.index, parsed));
re.lastIndex = index;
}
if (m[5]) {
// word - first check if this looks like a variable declaration
const local_var_re = /(\w+(?: *\. *\w+)*(?: *<.*?>)?(?: *\[ *\])*)( +)(\w+)( *\[ *\])*/g;
local_var_re.lastIndex = m.index;
const local_var_match = local_var_re.exec(text);
if (local_var_match && local_var_match.index === m.index) {
m = local_var_match;
// it looks like a local variable declaration
const typeident = new TypeIdent([new Token(text_index + m.index, m[1], '', null)]);
const local_var_decl = new LocalVariableDeclaration([], typeident);
let name_token = new Token(text_index + m.index + m[1].length + m[2].length, m[3], '', null);
let postarray_token = m[4] ? new Token(name_token.source_idx + m[3].length, m[4], '', null) : null;
const vars = [new LocalVariable(local_var_decl, name_token, postarray_token)];
const next = /( *=)|( *, *)(\w+)( *\[ *\])*/g;
let lastIndex = local_var_re.lastIndex;
for (;;) {
next.lastIndex = lastIndex;
let m = next.exec(text);
if (!m || m.index !== lastIndex) {
break;
}
lastIndex = next.lastIndex;
if (m[1]) {
vars[0].equals = new Token(text_index + m.index + m[0].indexOf('='), '=', '', null);
// variable initialiser
const { parsed, index } = extractExpression(text, next.lastIndex);
lastIndex = index;
vars[0].expression = parsed;
} else {
// another variable
vars[0].comma = new Token(text_index + m.index + m[0].indexOf(','), ',', '', null);
name_token = new Token(text_index + m.index + m[2].length, m[3], '', null);
postarray_token = m[4] ? new Token(name_token.source_idx + m[3].length, m[4], '', null) : null;
vars.unshift(new LocalVariable(local_var_decl, name_token, postarray_token));
}
}
local_var_decl.vars = vars.reverse();
tokens.blocks.push(new LocalVariableDeclBlock(text, local_var_match.index, lastIndex, local_var_decl));
re.lastIndex = lastIndex;
continue;
}
const { parsed, index } = extractExpression(text, m.index);
tokens.blocks.push(new ParsedExpressionBlock(text, m.index, index - m.index, parsed));
re.lastIndex = index;
continue;
}
if (m[6]) {
// brackets, scopes or semcolon
tokens.blocks.push(TextBlock.from(text, m.index, m[0].length));
continue;
}
// anything else is invalid
tokens.blocks.push(new InvalidTextBlock(text, m.index, m[0].length));
}
tokens;
// convert the tokens to their simplified form for grouping
let sourcemap = tokens.sourcemap();
// convert simple statements and expressions
let chunks = [
/(for)(\(?)([XY]?)(;?)(X?)(;?)(X?)(\)?)/g, // for -> F
/(if)(\(?)(X?)(\)?)/g, // if -> I
/(while)(\(?)(X?)(\)?)/g, // while -> W
/(switch)(\(?)(X?)(\)?)/g, // switch -> P
/(catch)(\(?)(V?)(\)?)/g, // catch -> C
/(case)(X?)(:?)/g, // single case -> Q
/(default)(:?)/g, // default case -> Q
/(return|break|continue)(X?)(;?)/g, // return/break/continue -> S
/(finally)/g, // finally block -> N
/(else)/g, // else statement -> L
/Y(;?)/g, // variable declaration -> V
/X(;?)/g, // statement expression -> E
]
let replacements = 'FIWPCQQSNLVE';
let ids = 'for_hdr if_hdr while_hdr switch_hdr catch case default rbc finally else localvar expr'.split(' ');
chunks.forEach((re,idx) => {
re.lastIndex = 0;
for (let m; m = re.exec(sourcemap.simplified);) {
let start = sourcemap.map[m.index];
let end = sourcemap.map[m.index + m[0].length];
tokens.shrink(ids[idx], start, end - start, replacements[idx]);
sourcemap = tokens.sourcemap();
re.lastIndex = 0;
}
})
chunks = [
/\{([SBVE;]*)(\})/g, // statement block -> B
/I([SBVE;])L?[SBVE;]/g, // if (Expression) Statement/Block Else -> S
/F[SBVE;]/g, // for loop -> S
/P(\{)(Q+[SBVE]*)*(\}?)/g, // switch(Expression){ Q(caseblock),... } -> S
/try(B)(C?B?)(N?B?)/g, // try, Block, catch/finally -> S
/do(B)(W?)(;?)/g, // do Block While -> S
/(?<!\})W[SVBE;]/g, // While -> S - this needs the no-pre-brace check to allow do-while to pair correctly
]
replacements = 'BSSSSSS';
ids = 'block if for switch try dowhile while'.split(' ');
for (;;) {
let old = sourcemap.simplified;
chunks.forEach((re,idx) => {
re.lastIndex = 0;
for (let m; m = re.exec(sourcemap.simplified);) {
let start = sourcemap.map[m.index];
let end = sourcemap.map[m.index + m[0].length];
tokens.shrink(ids[idx], start, end - start, replacements[idx]);
sourcemap = tokens.sourcemap();
re.lastIndex = 0;
}
})
if (old === sourcemap.simplified) break;
}
return tokens;
}
const expressions = [
'1 for(){}',
'a',
'true',
'null',
`""`,
`'c'`,
// operators
`1 + 2`,
`1 - 2`,
`1 * 2`,
`1 / 2`,
`1 % 2`,
`1 & 2`,
`1 | 2`,
`1 ^ 2`,
`1 < 2`,
`1 <= 2`,
`1 << 2`,
`1 > 2`,
`1 >= 2`,
`1 >> 2`,
`1 == 2`,
`1 instanceof 2`,
// assignment operators
`a += 2`,
`a -= 2`,
`a *= 2`,
`a /= 2`,
`a %= 2`,
`a &= 2`,
`a |= 2`,
`a ^= 2`,
`a <<= 2`,
`a >>= 2`,
// member, array, methodcall
`a.b`,
`a.b.c`,
`a[1]`,
`a[1,2]`,
`a[1][2]`,
`a()`,
`a(b)`,
`a(b, "")`,
`a.b()`,
`a.b()[1]`,
];
expressions.map(e => {
extractExpression(e);
})
const src =
`for (int i=0; i < 10; i++) {
do {
if (i) {
System.out.println("1234");
}
#
switch(x) {
case 4:
case 5:
return x;
case 6:
default:
return;
}
while (x > 0) true;
} while (i > 0);
while (x > 0)
System.out.println("1234");
}
`
class BlockRange {
get end() { return this.start + this.length }
get text() { return this.source.slice(this.start, this.end) }
/**
*
* @param {string} source
* @param {number} start
* @param {number} length
*/
constructor(source, start, length) {
this.source = source;
this.start = start;
this.length = length;
}
}
class TextBlock {
/**
* @param {BlockRange|TextBlockArray} range
* @param {string} simplified
*/
constructor(range, simplified) {
this.range = range;
this.simplified = simplified;
}
/**
* @param {string} source
* @param {number} start
* @param {number} length
* @param {string} [simplified]
*/
static from(source, start, length, simplified) {
const range = new BlockRange(source, start, length);
return new TextBlock(range, simplified || range.text);
}
toSource() {
return this.range instanceof BlockRange
? this.range.text
: this.range.toSource()
}
}
class ParsedExpressionBlock extends TextBlock {
/**
* @param {string} source
* @param {number} start
* @param {number} length
* @param {ParsedExpression} expression
*/
constructor(source, start, length, expression) {
super(new BlockRange(source, start, length), 'X');
this.expression = expression;
}
}
class LocalVariableDeclBlock extends TextBlock {
/**
* @param {string} source
* @param {number} start
* @param {number} end
* @param {LocalVariableDeclaration} decl
*/
constructor(source, start, end, decl) {
super(new BlockRange(source, start, end - start), 'Y');
this.decl = decl;
}
}
class InvalidTextBlock extends TextBlock {
/**
* @param {string} source
* @param {number} start
* @param {number} length
*/
constructor(source, start, length) {
super(new BlockRange(source, start, length), '');
}
}
class TextBlockArray {
/**
* @param {string} id
* @param {TextBlock[]} [blocks]
*/
constructor(id, blocks = []) {
this.id = id;
this.blocks = blocks;
}
get simplified() {
return this.blocks.map(tb => tb.simplified).join('');
}
sourcemap() {
let idx = 0;
const parts = [];
/** @type {number[]} */
const map = this.blocks.reduce((arr,tb,i) => {
arr[idx] = i;
parts.push(tb.simplified);
idx += tb.simplified.length;
return arr;
}, []);
map[idx] = this.blocks.length;
return {
simplified: parts.join(''),
map,
}
}
/**
* @param {string} id
* @param {number} start
* @param {number} count
* @param {string} simplified
*/
shrink(id, start, count, simplified) {
if (count <= 0) return;
const collapsed = new TextBlockArray(id, this.blocks.splice(start, count, null));
this.blocks[start] = new TextBlock(collapsed, simplified);
}
get source() { return this.toSource() }
toSource() {
return this.blocks.map(tb => tb.toSource()).join('');
}
}
parseBody(src);